That depends on how much time you have to devote to this. In the beginning you may spend long hours promoting your site.
In time you will get the hang of what needs of what needs to be done and will be able to complete all of your promotional task in a few hours a day.
Most importantly, put yourself on a consistent schedule. Make a list of the task you need to complete, all of them. Decide how much time you will have and when you will be able to perform these tasks. Stick to that schedule and chip away daily.
The best advice is to keep all of your tasks on a consistent daily schedule. It is better to spend 2 hours daily to site promotion that to spend 14 hours in one day only once a week.
How much time should I devote to maintenance?
Again, this depends on what types of site you have. Only you can decide how much time you should devote to maintenance.
If you have a content related site than you should update your pages regular so as to keep your viewers coming back.
If your site is not the type that needs to be update often, or your information will remain the same, I suggest that you update from time to time anyway. Change the design and layout to keep your site interesting.
