How soon after preflower will you notice first buds?

The title of this says it all, How soon will you be able to see the first clusters of buds

Shortly after you start flowering.

MajoR_TokE is right. I had my plant preflowering in veg and once I started to flower I noticed nice little buds within 4 days.

I try to wait for preflowers in veg before i flower.