Despite the numerous times it is claimed, ball pythons do not produce sperm plugs. For starters sperm plugs are placed in the female to prevent other males from knocking her up. Obviously ball pythons do not do this. What people refer to as sperm plugs are just shed of the man parts and some other bodily stuff with no baby making potential. Therefore they are not really indicators of male being ready or not. However we know there are 300 gram males that have successfully made babies, so obviously they do get baby making potential very quickly. I have also talked to a few breeders who say they pop their males and remove this shed before breeding and feel they have a better season because of it.
Sometimes it takes unproven breeders time to figure out whats going on, wait til you see one your male trying to do things to the wrong end of the female. Also if the female isn't interested it isn't happening. A few weeks is hardly any time to worry. Keep putting males in and let them figure things out.