You can do it now if you want. I never did it more than once, so I can't say. You probably can, I would think, but when you fim you'll get 3-4 new branches coming out the top so, what, you want to fim each of these as well? Seems like a bit of overkill to me.

Don't know how each will respond. I did mine with a Nirvana Afghani and it worked pretty well.