Cooling system burping on 4000 or I5's

[DK]

Replaced the leaky water pump yesterday and wanted to burp the cooling
system. I removed the coolant reservoir cap, let it do its business.
Massive bubbles from the bottom hose and lots of hot air from the
overflow hose. After some research I found out that am supposed to use
the screw on the radiator. Removed it, let the reservoir cap on, let
it warm up, but it was steaming like no ones business. Am I doing
something wrong, or am I supposed to wait till only coolant comes out?
(no visible leaks, no white smoke from exhaust)

TIA,

Dave