There is really no correct answer to this, it all depends on how much you want to do, and how much time you can make for it. The only thing that I can say is that it would benefit you to be as consistent as possible with your writing schedule.
For example, I write the next part of the story for my novel in shorthand in my notebook on the train to and from work, which is approximately 40 minutes each way. When I'm home I put aside an hour every night to write up my notes onto the computer and add anything else that I can, as well as look over what I wrote the previous day. The next day I rinse & repeat, and then take the weekend off.
It doesn't have to be every day, but this works for me, yours will likely be different. What this does is allows me to keep on writing constantly, and that is time that is put aside for my writing, and I don't feel bad if there are other things to do (chores etc.), and I don't feel like I could be doing something else that is more fun.
Even if I can't think of anything to write I stay at my computer and don't do anything, which helps to reinforce in my mind that I should be writing, so that I don't slack off the following day thinking that I'm stuck. Now whenever it gets to that time my mind is in the routine of being prepared for writing, and it's easy to sit down and get at least something done.
For deadline-making, I would suggest having a long term goal, and then breaking that down into shorter term goals. For example, I want my book to be done in a year, so for approximately 25 chapters that means if I complete a chapter every 2 weeks I remain on track. This can vary sometimes, but as long as I am at around that pace I feel comfortable with my progress.
So it entirely depends on what works for you. For further tips try this SE question, the stuff on there really helped me.