Glamour question

Glamour's third level feature states:

In addition, immediately after you cast an Enchantment or Illusion spell using a spell slot, you can cause a creature you can see within 60 feet of yourself to make a Wisdom saving throw against your spell save DC. On a failed save, the target has the Charmed or Frightened condition (your choice) for 1 minute. The target repeats the save at the end of each of its turns, ending the effect on itself on a success.

It doesn't say anything about your turn, so is there any reason to believe I cannot cast silvery barbs (enchantment spell) as a reaction on someone else's turn, to charm/fear an enemy?  I'm pretty sure I'm not missing anything, but would like to confirm.  

Ok cool, I was worried about missing another rule, but I was pretty sure that I'd read it correctly.  It's nice to get a bit of confirmation that I hadn't missed something obvious.

This would also work with spells cast as a reaction using the Reactive Spell feature from War Caster. For example, a Bandit runs away, you cast Hold Person on him, then charm or frighten his buddy. That's a pretty potent reaction.