I'm currently a Swashbuckler Rogue 4/Bard 1. This campaign goes to level 20 and my end goal is Swashbuckler Rogue 14/Valor Bard 6. I'm leveling up, so what leveling order should I use? Not just for this level but overall?

In general when multiclassing you want to take classes in 4 level chunks when you can, so as not to miss out on ASI's. In this case, though, you might want to put your next five levels in Bard if you're going for Extra Attack. Why don't you tell us a bit more about your character and the intended playstyle? Then we can help you out more.

I play a Swashbuckler/Swords Bard and I'm having a ton of fun with him: https://ddb.ac/characters/2725951/JURQnk

This was my leveling progression and why I did it that way:

I had always been a fan of Eilistraee and her sword dancers and wanted that grace to be a part of this character's gish style, so I reverted my character back to the 4th level Swords Bard and when I hit level 5 I took 1 level of Hexblade, reskinned as Eilistraee's Moonblade. Now my Dex and Cha were even at this time so there was no sudden disparity in sword skill to smooth over. We had also just escaped from a foray into the Underdark. The session was unavoidably cut short due to a scheduling issue and my DM was forced to handwave and teleport us back to Waterdeep and I asked him if it was okay to say that the sound of mysterious hunting horns led us back to the surface, which allowed me to write a dream sequence where my bard met Eilistraee and received her blessing. This allowed me to pick up Shield as well as proficiency with shields, which I reskinned as a cloak wrapped around an arm so I could be a spanish style rapier and cloak fencer. Booming Blade rounded out my magical melee skill set.

Then I started taking levels of Rogue, becoming a Swashbuckler at level 8, and getting my second ASI at level 9, which I put into Charisma. This means I'm using Charisma for melee, for spellcasting, and as an initiative boost, which allows me to grow as a swordsman and a spellslinger at the same time. Plotting out my levels ahead of time I intended to end roughly at Swords 6/ Hexblade 3/ Swashbuckler 11 because that maintains a character who is mainly a charming swordsman (I love Panache and the idea of just being that silver tongued that I can do that without a spell) but also has enough magic tricks up his sleeve to make that swordplay flashier. I wouldn't have any spells higher than 3rd level, which I viewed as a benefit since I mostly wanted spells that were utility and enhancement and not spells that were huge game changers in and of themselves, that didn't fit the character concept I wanted. At level 9 (Swords 4/Swashbuckler 4/Hexblade 1) any level I took would result in meaningful growth, which allowed me to still be responsive to the plot in how I progress in my plan. I just hit level 10 in my game, for example, and we're currently in a plot arc that has open terrain and military leanings so I took that level in Bard, allowing me to better support my Fighter partymate in his quest to take over as warlord of the local orc horde.