Take a picture if possible and post it. Mine have been flipped for 4 days and I have preflowers ... all showing sex. Do you even have that? Are the plants from seed or are they clones? If seeds, did you have alternating nodes prior to flipping the lighting schedule?
I veged for 3 weeks 18/6 then i started flowering they are from clones they are all showing female its been 21 days sense i started flowering 12/12 and if a light leak would make a differents i do have a little one from my grow tent were the inline fan is coming out from and it reflects off my mylar
A small light leak should not stop your plants from flowering, If they are showing pre flowers it means tueurs are in the flowering stage. Be patient in another week or two you will see buds, If not then worry.