oie I just wrote you this long detailed message, and hit backspace one too many times and it erased everything! So this is going to have to be a little shorter, but email me back if you have any questions!!
My story,
I was still in school when I had my daughter, so I took one semester off, then went back full time. This was okay because she was 5 months old and I had a sitter come to my home and watch her for less than 4 hours a day, 3 days a week. Then when she turned 1 I put her in day care for about the same amount of time. I was okay with this because it was good socialization skills and it helped her be okay with me leaving her. However, she was ALWAYS sick!!! Everytime I would get her better and send her back, a couple days later she would develop something new. It was AWFUL! I graduated a year later and took her out of day care and she has not been sick once sine then! (and its been almost a year).
I woudl say that when to go back to work is really up to you and your twins. They should be able to go several hours without nursing so you should be able to go to work and they will be okay.
One thing to keep in mind, which I am sort of struggling with now. Teaching is a serious commitment. You can't just take a day off. Even though you have your degree, you might want to think about doing something with a little less responsiblity. maybe somewhere that you frequent regularly, like a childrenst store at the mall, your fav store at the mall, picture studio. That way you get more income, but the schedule is flexible so that you can stay home and take care of a sick one if you have to. I am not sure where you live or what your situation is, but here where we live, daycare for one child is about 800 a month (for an average school). To me that is a lot of money, and to go to work to pay all that for someone to watch your kids all day doesn't seem worth it. Know what I mean?
I work for child and family services (social work) and I work one or 2 nights a week (4 hours) and then am on call one weekend a month. I can make what most people make in two weeks, during that one weekend. It works out really great this way. Something like that might work for you. Or working at a day care, you can get a little income, a discount for your twins if they attend taht school, and if you have to stop to nurse them you are right there.
I get both worlds. I will be starting teaching as well in the fall, but only part time. My daughter will be in preschool, which she is ready for and needs... So I still get time off when she does and I don't have to put her in daycare all day.
Hopefully this helps!