I'm married (9 years) and have 2 kids (throw in house mortgage as well.) I've been working on start ups for the last 3 years. I left a very good, high paying, stable job to work with startups. The first key thing is getting your wife on board. There is a lot more risk and stress with startups. Make sure both of you understand this issue. Money is already a big stress on marriages and you are about to make that situation worse in the short term. The other big issue (at least in the states) is health insurance. It costs a lot more that I would like.

The startup I work at is a great fit. We are boot strapped and profitable. We are not trying to be the next google/twitter/facebook, so slow growth fits our lifestyle fine. There have been lean times over the last year which adds financial stress, but I have fall back plan of getting a real job at any time which provides a nice safety net. It pays to have a good network to leverage when you need it. I work from home, so that allows me to work mostly normal hours and still get to see my wife and kids a lot. I carve out a few evenings to put in extra hours. I also carve out date nights with my wife.

So I don't see any issue with being a startup and being married. There is never the perfect time to start a startup. The best time is now.