Contacting a potential PhD advisor
Yes, if you have the opportunity to visit for a few minutes in person, you should do that. Ask if there are any further steps you should immediately take.
For an email reply, a few more days of waiting is better, but a quick visit is likely fine. Express your excitement about the future, etc.
In these perilous time, few now have the opportunity to do this sort of thing in person, but it is the preferred way. And, your situation isn't very typical since you probably already know the person and you are an &quot;out of cycle&quot; applicant.