Start with some easy, fun books. I'm not saying you need YA-level books (not that there is anything wrong with reading YA when you're an adult) but there are plenty of very good stories out there with an easy, breezy writing style.

And try not to focus on page numbers or word counts. If you want a schedule, make it time-based - 20 minutes a day or whatever works well for the rest of your daily life. Whether that means you read 20 pages or 5 pages, you should like what you're reading and be eager for the next installment. Enjoy that time, enjoy the story.