I did it just recently actually. It's my first grow. It works. I fimmed first because I wanted to control height on a Sativa and then 2 days later I realized it wasn't going to be enough so I went down and supercropped them about 6" down from the fimmed top (I had a 12" plant)
The plant will want to heal it's stem first so it will attend to that before regrowing the FIM. Keep this in mind because if I had known that I would have supercropped first and then fimmed for faster fim growth with the supercropped(healed) stem.
Here's what it looks like supercropped,
(You can see two big knuckles on that branch bent towards the wall) and then the fim growing after the stem recovered
Should be totally fine