Hi all,
On the '74 Classics, ALL take-offs are 'packs off'!
That's whether it's a performance requirement or not, and normally the FE turns on the packs, one at a time, starting about 300' AGL.
That's except in the case of an engine failure, when he will be very busy anyway, unloading the pilots, so they can get on with flying the aeroplane, and he then turns on the first pack at the same time as the first flap retraction, the next when he feels the aeroplane is performing, and leaves it at that!
If it's really hot, as mentioned earlier, one or two packs are run from the APU until the flaps are up.
Great things, these FEs!!
Cheers...