The best thing is to have a consistent schedule you can keep up with. So as long as you're doing that, you're starting out in good shape. A gag-a-day style comic might update every single day, but with a story comic that can get overwhelming, so once a week, or a few specific days a week is generally better.
How many pages you choose per update is up to your discretion, but again, being consistent seems to help.
The nice thing about spreading out over a couple days is that it gets you a little more exposure on the front page. But I post one page a week because that's what I can maintain long term, and that's pretty normal.