Well ive been told to expect about 100g per plant by a mate that grows regularly.
Its ok to guess on the light wattage and stuff but the variables make it impossible to be precise.
If youre growing 24, you must have some room?
Mine are in a 1.2mx1.2m tent. When i got 6 plants to start with i wondered whether i should have got 12.
Im glad i stuck with 6, ill show you why. And if i get 100g per plant ill be well happy

Any more than 6 and i would have had no room!!