Are you flying
big iron or light a/c? In light a/c, you'd typically (VFR)
climb to at least 400 ft AGL and past the departure end of the runway before
initiating a turn, unless ATC asked you to turn early AND you felt it was safe
to do so. When IFR, ATC will normally give you an initial heading to turn to
(usually as part of the clearance) before contacting departure, and I'd want a
minimum of 500 ft. AGL before starting the turn. I'll let Bala
and Co. talk
about the big iron.
In commercial aircraft, ATC usually tells you your alt, heading, and when to
turn. In light aircraft too (IFR) you use the instructions on your SID
(Standard Instrument Departure). I'll read an excerpt from the Cincinnati Eight
Departure for RWY 36L: " Fly runway heasing until 0.5 DME north of runway
localizer, then turn heading 330 degrees, maintain 6000 feet, expect radar
vectors to filed/assigned route. Thence expect clearance to to requested
ten minutes after departure." This explicitly explains
what to do! :-) Of course, SIDs differ (most don't use ILS freqs as SID navaid
DME indicators). you generally climb until you reach that assigned altitude.
what some adventures don't portray very well is when the climb to your
requested flight level begins. most adventures request that you stay at the
initial altitude (in this case 6000) for the full ten minutes. In real life,
it's usually just about a straight climb up to your flight level because they
clear you to your requested altitude before you reach your initial altitude.
Hope this helps!