There will be never a perfect time. Is like me, there is never a perfect time to get married, you will spend the rest of your life preparing things and there is no limit in perfection.
I in my case I decided to stay single, but speaking from people I know, you just have to move forward and do it, the good thing you guys have college degrees, you are ready to go. The sooner you guys do it specially if you are in the early or before 30s, the better will be, as long as you are passing 25 because before is just way too young, I'm sure you know what I'm reffering to.
Yes it's expensive, but later the pressure will make you make more money, at least is what I have seen, people really open their eyes and do things a lot more efficiently. As far as your goals of a master degree, you don't have to get it all now, you can put your career on hold while you also take care of other things in life, like having a child if you have a good marriage, that looks like yes, because life is not about a career, unless you just want to end up with a degree.
Find the right balance between what you WANT to do, what you CAN do, and what you DON'T WANT to miss. I would say you have found the crest of the wave and you are going at optimum speed (lets say surf-terms), because you aren't in your early 20 anymore, so the balance point for what you described (age, degrees, goals) looks like is the time to take actions. A friend told me the younger the better, because when you are 50 you would like to see them older and have more energies to play with them when you are in your early 30s.