How long should i leave my plants in veg after I Fim?

I am new to the whole fimming tech. So I was wondering how long after, before I can begin flowering?

Give the plant time to regrow the bud sites you just snipped. Once you see some shoots coming and notice good node development, then you can consider tossing her in flower. Just remember the more nodes you start with going into flower, the more bud sites she has at the ready to produce.

At least a week but really you should do what doom said and wait until you see healthy strong new shoots were you fim'd/topped.