Once it has a min of 3 sets of nodes you can top. Normally 4-5 is best. But, as thees are fems. It's best to take your time. See what nodes grow strongest. As you might get the 1st set are really slow. So you can remove the 1st set and then decide where you want to top. No need to rush it. Top when she's in top form. Well defined nodes. Once the set is up where you want to top above its best to allow them to mature some, and then either remove the 1st set if they are small. And so on.
They are fems. So no need to rush it.
As you have 4. Why not top 1 with 3 sets, another remove the 1st 2 sets and then top above the 7th (so that plant will have 5 sets) and so on. Do some experiments.
Good luck