Sometimes squads throw stuff straight away, sometimes they dawdle for a turn or two, it's out of our hands..
I just ran this test below
PIC 1 - The squad has an AT-mine and a gren bundle as the M8 stops outside..
PIC 2 - Away goes the AT-mine and scores a hit. (Note ATM's are invisible in CM because in real-life somebody must run up and plonk it on the tank, so CM abstracts it by just having a guys arm swing)
PIC 3 - Fourteen seconds later they throw the bundle (it killed the M8 a fraction of a second later)..
CONCLUSIONS -
They threw an ATM and bundle in the same turn, not bad.
Squads can throw ATM's and bundles from houses.
Incidentally I never ordered the squad to throw anything, it did it all on its own initiative.