Id look at this question not as "when should I launch", but instead "by when do I want x amount of traction."

Q4 is of course the "money months" when it comes to digital publishing, as ad spend increases for the holiday season.

You're going to be unfortunately missing this, but you can absolutely launch successfully in Jan. as you plan, and build your strategic road map to hit the key goals that would put you where you need to be for this time next year.

Launch, keep metrics, tweak your campaigns, and stay consistent with results year round!