Write a few chapters before posting or you will regret it.
If you want to build a following, regular updates on a fairly short time frame (at least onces a week) and important and while it might seem easy at first to post as you finish to a regular schedule all it takes is a few bad days or a bad week and suddenly your schedule is screwed and you're falling behind, you have to go on haitus to catch up and then it's really hard to come back sucessfully. For your own mental health and your series' future, build a buffer.
It's also just really useful to take a little while between finishing and posting so you can look at your chapter with a bit a distance and can look at it objectively, reading what's there rather than what you think is there when proof reading.