Since it is currently 3:30 PM EDT, the next PM time is already ongoing. If you meant how many minutes until 12:00 PM (noon) today, that time has already passed. If you want to know how many minutes until the next PM hour after 3:30 PM, for example, 4:00 PM:

• From 3:30 PM to 4:00 PM is 30 minutes.

If you clarify exactly which PM time you mean, I can give you a precise answer!