I have one deep on so far. Do I really feed them until I put supers on?
Of course you do not feed. What is the idea in that, as you supposed yourselves.
The colony grows along the speed of brood cycle. You cannot speed up the progress.
It is an advantage that there are minimum amount of syrup in the hive because they get honey outside.
Let the deep first become full of bees. Then give another deep under the present box.
Colony occupyes the foundations when it has resources to it.
If you give a excluder and super next, the hive is not ready to get surplus. The super is for nothing and if the queen is good, there will be lack on laying space in the deep.
when a colony is fastly growing, it uses almost all food and there is no honey in super during next one month.
I know very well what happens in hives in that time.
Our dandelions and apple trees will be in bloom at the end May = after 2 weeks.