Are you implying that, in case there are no pokemons roaming:
# of frame advancement = Target frame - Monster frame - 10 (seed verification-optional) <<< ?
That's correct.
I apologize if this sounds stupid, but I have to ask. Where are there level 50+ Pokemon in Heart Gold that I can use to find my initial seed? I'm trying to use the Pokemon at the beginning of Mt. Silver, but they won't work. I don't want to have to get to the end of the cave every single time I want to find my initial seed. :/
Use "Find Seed by IV Range" in the Seed Finder and give a Rare Candy or two to that Mt. Silver Pokemon, using an IV calc to narrow down the IVs. Sometimes you don't need to use a Rare Candy.
At some point you will be able to input the captured critter's Hidden Power type and need no Rare Candies at all, assuming it is high enough level.