I'd let them grow a few days more and then top or fim them. I'd recommend topping for your first time as it is pretty common and easy. I like to let my plant get to 6-7 solid nodes and then top down to 4. This gives the plant a strong base before topping and nodes 3 and 4's branches will become the main 4 for the grow then. Once the plant gets a little wider you can tie down node 4s branches a little to let 3's catch up to them in height and then the 4 will grow evenly. Best part of this whole thing is you will get lots of recommendations and none are wrong!
As for the roots, there is nothing wrong with that at all. However when they get to the bottom they should curl back into the plant or the tips will kind of die off (which is fine). If they aren't then that means that are able to find water out of their pot. If that is the case then make sure they are not sitting in their own runoff water. Looks like you are having some good root growth! That is a great sign. Really you don't have much to worry about in terms of getting rootbound in coco. You should top/fim them and let them recover and then transplant to final pot.
As for the roots, there is nothing wrong with that at all. However when they get to the bottom they should curl back into the plant or the tips will kind of die off (which is fine). If they aren't then that means that are able to find water out of their pot. If that is the case then make sure they are not sitting in their own runoff water. Looks like you are having some good root growth! That is a great sign. Really you don't have much to worry about in terms of getting rootbound in coco. You should top/fim them and let them recover and then transplant to final pot.