Correct me if I'm wrong (as if you guys wouldn't
), but I don't think autostart is basic on the A320 (perhaps it is on the more recent production). No autostart means someone needs to be 'heads down' during the entire start sequence unless you want a tailpipe full of molten metal.
As a propulsion guy, 3 minute warm up is really short for initial start to takeoff power. If you're talking a quick turn-around it may be OK since the engine never really cooled off, but after an overnight that's a big thermal shock to the engine (compressor rub/permanent performance loss - in an extreme case it can cause a surge). Five minute warm up is the minimum I'd recommend.