Do i need to flush?

Ive been growing for almost 3months, and havnt started flowering as of yet, however i have been using Ferts throughout and only maybe 12 leafs have a few burns ( dry yellow spots on them) when or do i even need to flush ?

I also repoted them into a bigger pot so does this mean i still need to flush?

If you are showing nute burn then it would be a good idea to do a flush on them. Water them normally with no nutes for a week and trim off the dead shit.
When you start feeding them nutes again, only feed them half of the recommended amount for the first week, 3/4 the second and then full amount from then on.

But if you start to see nute burn again, drop back down on the amount of nutes you are giving. It may just be that your plant either doesnt like them or you have some residual in the soil.

Good luck!