Follow label directions. What are you spraying with and what is it about your lawn that makes it attractive for moss? Generally speaking moss needs compacted, nitrogen lacking, shaded soil. Omit one or two of these and moss can't compete with the grass.

tj

Thanks tsuga...but that's my problem, there is nothing about hold long one must waid to seed after spraying in the literature/instructions. Is there a "usual" time????

What are you spraying?

tj