As the person who reported your post pointed out, this has been discussed at length in the old Fire Mage Compendium, the author of which has since retired, hence Guromin's more recent thread. I recommend you search there: Cataclysm Fire Mage Compendium
I am moving your question to SQSA, as I don't mind the question in general, and because the fire thread changed hands as of 4.3.3, it's understandable that your search didn't turn it up in the new one.
I'm having a few issues deciding when to cast my first Combustion.
My issue is with Stolen Time, by the time I get it to reach a decent amount of stacks all my spell power procs have dissapeared. On the other hand, if I use Combustion with all my procs (including Foul Gift of the Demonlord proc) I have a really long cooldown until my next Combustion and I don't have enough Stolen Time stacks to reach the extra tick on Combustion.
I feel like at the moment, I'm doing more dps when I use it with all my procs (but I don't know for sure). This might have just been to RNG granting me a nice ignite on those tries, or the fact that I'm using Foul Gift of the Demonlord (1 extra proc to align).
If I am doing more dps when I use my first Combustion with all my procs, do you think this will change when I replace Foul Gift with WoU?
Has a general consensus about when to use your first Combustion been reached? I couldn't find the information in the OP.
(Also, if it's important, my mage is a very new alt, and only 388 ilevel at the moment).