If you're going to be using a constant supply of chlorine, like trichlor in a floater, the amount in the trichlor should be enough. It will take awhile to raise the stabilizer (a few weeks or even maybe a month or two) but if you always have the trichlor being circulated around the pool, then it should be fine.
However, if you're planning to use any other type of non-stabilized chlorine,, then I would add the CYA separately.