Alrighty, so I am a newish dm, been running a session with new and seminew players in a homebrew campaign. The sessions have been going swellish, their are rough spots. The folks now have a gist of playing them game, what to do and how to do it. But things aren't running as smooth as I feel like it could be, which that I feel was a mistake on my end, I started the folks off at lvl 5 instead of 1. And as the game progress, I feel that I skipped a lot of time where the players could get to new their characters and better understanding their abilities, for we spend a lot of time looking through rules, because their is just so much stuff to keep track of, they didn't have a slow enough space to learn everything, and now they are level 6, it just added to the confusion, more so with the new players, and myself trying to learn the abilities of multiple class at once. So here's my question, you think it would be a good idea to go, start from the begining, and say alrighty now you got the jest of the game, joke characters aside. Let's spend a session, make new characters, start at level one, and spend a more slow time at learning characters and actions, and get more development, instead of kicking you straight into it.

I would have 2 ways to approach this. Either 

1- sit down and discuss with the party weather to put this session on hold and start a new on with a lower level and progress with the skills and rules slowly as you level up

2- sit down with the party and instead of continuing the campaign, spend the session (or 2) going through each characters abilities, discuss how they work and come up with theoretical situations the players could use them in etc 

Even experienced players and DMs rule check, but ultimately the players are responsible for knowing their characters and how they work. Granted give time to look up spells/abilities etc but they should still know the basics of what their class can do.

Hope you get it sorted and playing smoothly soon. :)

I would discuss these thoughts with the group before making a decision. It might be that they recognise some of it, and agree that rolling back to a lower level would be nice. But it could also be that they are actually really enjoying their current setup, and want to grow and use these characters. IT probably comes down to a balance around what they are enjoying most, and how long you have already invested. 

But it sounds to me like something where I would consult the players. Even if there is a split in preferences, at least everyone will have an opportunity to state what they enjoy or what they would like to change. 

I do plan on bringing it up, thanks for the advice. 

If it helps, I've got a group of players that has gone from 1-7, then 1-10 in two different campaigns, and one thing is common among the two: level progression can easily outpace player familiarity with PC abilities. I feel this is more common among new/-ish players that are trying a character for the first time. 

As for solutions, consider throwing in some side quests that don't advance plot so that the players have the opportunity to drive the new PC around a bit. Slow your progression rate down by adding more busy-work/distractions/PC backstory quests, so that they have time to learn the new things while the plot stays on pause. This, of course, requires that your plot be in a place that it can pause for some time. 

I second the idea to give the players a slower leveling progression and have them cut their teeth on a difficult quest. They're already invested in these characters, so give them a chance to get to know them better before you abandon ship.

You can also do a few non-canonical sessions (like beach episodes, carnival episodes, battle royales) that give them a chance to use their combat abilities in a way that won't affect the story. Also, dungeon crawls are good adventure inserts that test a lot of their skills in a short period of time. 

There were times in my life when I tried to know the players' characters better than they did. It was a bad DMing habit, and I've grown out of it. I do occasionally find myself saying, "I can't remember it for you," but I prefer that to the alternative... That said, the early levels are formative. They're where you get to see the classes growing into their roles. If you have to start later than 1, a good middle ground is 3, because every character has their subclass but they also have time to learn...

In my mind, starting fresh isn't a bad idea for this particular situation.  You mention new players, who now have a decent understanding of the game and so forth and I would wager some are wishing, inwardly or visibly, they had a different character.  I think that idea is certainly worth throwing out to the group as an option.  They've had some time to experience some things with characters who had a handful of options and abilities. Now they can start fresh, knowing a lot more about how things work and be able to slowly accumulate these new abilities and skills.

As some mentioned, even veteran tables have rule check moments, as nobody knows every feature of all the subclasses and stuff, but it does noticeably get less and less as the table plays more and experiences firsthand these different skills and such.

The options presented are all viable.  Reset from level 1 and everyone does better from the start would work.  Taking a full session to simply go over all the classes where they are now and get to know what your class can do and what that means, in some cases.  I'd present both to the group and see what they all think.  Sometimes you need to slow down to go fast.

Slow is smooth. Smooth is fast.