I agree with frog, don't worry about super cropping if this is your first grow. If you are dead set on this sort of growing it would be way safer to LST your plants for your first grow, there are videos on Youtube on the subject. I lollipop and I do it rather early because I hate fighting branches when I am watering. I am also fairly aggressive with trimming and have had no problem what so ever with plant growth or with yield. That being said there is a ton of people who hate lollipoping and refuse to get a pair of trimming shears near their plant. Don't get me wrong here don't go crazy trimming or you will rob your plants ability to use light for growth. Topping is simple so I say go for it and if you mess it up you end up FIMMING which works out well anyways. FIMMing means FUCK I MISSED MAN or just FUCK I MISSED, and it is just that. So if you top and miss you end up with 3 or 4 new tops instead of just 2, either way you win unless you really mess up and just plain cut the whole top of your plant off. Lastly put some pics up so we can help you.
Speaking of pics here are some girls that have been lollipoped and trimmed up. Notice that in the canopy pic most of the bud sights get light and you can even see some of the substrate through the canopy, but there is still tons of fan leafs. Now don't freak out yours will be bigger than this, these ladies are growing in a very small enclosure. Totally off subject but I love micro growing, I have just about every type of setup you can dream of accept LED and I think I have the most fun playing with my tinny plants lol. Ok enough out of me good luck man hope it helps.