Thermostat

I just put a new thermostat when i took the
old one out of my 03 Infiniti G35 it was only
the housing didn't have the inside piece now
my heat works didn't before now i put fluid in
the radiator as told let it worm up till the
temperature gage is in the middle ready to
drive drove a little over heated so i park it the
reserve bottle that connects to the radiator
was bubbling as told would happen then my
guy said keep the hood open let it cool for
like 45 min then refill till fluid hits the top did
that warmed the car again ex ex had to put a
little more fluid haven't drove it yet started it
last night a good 45 55 min and it was fine
now water pump is good fan and fan motor
is good. Now my question is that someone
told me before starting it this morning
remove the radiator cap and reserve cap
then start it he said it will probably blow
some fluid out but it's normal can anyone
please help me with a 2nd opinion on this
advice that was given to me or co sign like
would it really be helpful and what's the
porpoise for doing this need help ASAP
anyone.....thank you and a great morning to
all. WC.