While you should spend as much time as possible marketing your books, the key is consistent steps everyday, so if you can only devote 20 minutes a day to marketing, then be sure to be consistent with that.
Here are some resources for what you can be doing to market your books:
- The Author Hangout Ep 022: “Marketing, Networking, & Publishing”
- The Author Hangout Ep 016: “Getting Book Reviews”
- 10 Essential Marketing Tips for New Authors
- The Author Hangout Ep 003: “How To Find Your Readers”
- 3 Hot Tips for Finding Your Audience on Goodreads
- The Author Hangout Ep 013: “Great Book Marketing Ideas”
Read through these resources and make a plan for the types of marketing you can do, then set a schedule and stick to it daily and work through the plan.