When to follow up with a potential supervisor after sending referral contact details
It is impossible to say in general. It is a busy time for many academics. If you are friendly with your two referral contacts you might ask them first if they have been contacted. If they have not, then there is some delay and you should probably just wait a bit longer. 

If the start time of the degree program isn't soon, there is little reason to panic. But if you want/need to start soon, you may want to contact the potential advisor sooner. 

However, in some places, acceptance to a program isn't controlled by the individual faculty member but by the university. In that case, make sure that your application is proceeding normally. He may need to wait for a signal from them before he spends time on a potential student. Other places, professors directly hire into their own labs.