There is no N such that your algorithm is guaranteed to terminate before N flips — even for a single bit. The complexity class in the worst case (100% T) is infinite; it’s only the average cases that have something reasonable.
To borrow your phrasing:
If you only have a stochastic algorithm, I think you should have to say so.
As I mention elsewhere, for a coin where P(H)=0.75, with 600 flips, the probability of not having received an answer is less than 1 divided by the number of atoms in the universe. While this is not 0, neither is the probability of the atoms of the coin lining up just right that it falls through the table, producing neither H or T. Theoretically and practically we do generally consider these kinds of things immaterial to the problem at hand, perhaps papering over them with terms-of-art like "with high/extremely high/arbitrarily high/ probability". They all mean roughly the same thing: this algorithm is "essentially guaranteed" to terminate after n flips.
I think this kind of undermines the point, and goes a long way to showing that sometimes the best way to communicate actually is in a way that is unique.