My understanding is that when the TOGA is pushed for T/O (prior to 50 kts) without VNAV armed the following events occur:
1. The thrust levers advance to the selected T/O thrust (THR REF) and the vertical mode will be TO/GA.
2. At 65 kts the autothrottle annunciates HOLD
3. At 400' the autothrottle again indicates THR REF
4. At the selected altitude, the vertical mode changes to ALT but the A/T remains in THR REF and the aircraft accelerates up to the flap placard speed or VMO as applicable.
Therefore SPD mode needs to be selected or alternatively, select FLCH SPD while still climbing.
Regards
csd