I never use charms on perception anmore.  Perception is an awesome set, but at a point it's just clutter.  I literally just pulled 100 pieces for cvc and kept only one piece.

so at some point it will not matter. Bit for now, if you need it, use boot charms.  They are the hardest to get.  If you get boots most likely won't be speed.

for now you seem a point where you just need the gear, so i wouldnt worry to much about using charms every time you craft perception items for now, only craft the 6 star pieces. As for substat charms etc i think this is more of a point where you have champions built but they are missing a few key items with certain stats that you need, so id hold off using sub stat charms personally until you know exactly what it is you want.

Agreed on not using rank / rarity charms for Perception.  IMO those should only be used on DT and Forge Pass sets.  Using substat and slot charms would be okay though.  Accuracy + Boots is what I usually try for Perception gear.

For other sets you wanna use charms that match what you want to get from the set.  So Crit Rate / Damage for Lethal, HP% for Bolster, etc.

Trying pumping the billows to get the iron really really hot and then quickly hammer out the gear before quenching it in the oil. Really high heat is the key to getting speed as your primary stat. I did this and I got a great pair of leather boots.