my air con is fairly similar, takes a minute or two.
the other thing i have noticed (especially when i went on holidays recently with a huge load) it seems that at high rpms the a/c cuts out, im thinking maybe for more power or something ...
i first noticed it pulling out onto the highway etc, floor it to 100 and it seems the air goes warmer, once you click her into 6th and start cruising it goes back to normal.
i noticed it a few times when on my holiday, had a boat full and the back of the ute full, i needed to go 3rd gear up a few hills to hold 100km's ....
has anyone else ever noticed this ?