I have always placed on supers when the top super was generally 70% or so filled with nectar even though uncapped. I would also lift the top super and I could tell how it was progressing. This year has been an unusual year, I have a few hives where 2 supers are generally full, the 3rd was only 15% but just loaded with bees, so I added the 4th this morning to give them room. Now that super is filled with bees..... is a split in order or should I just let them do their thing. I am using single deeps with a queen excluder. I am interested in honey and not more hives.