I'd dated a little (and been through breakups that were painful despite the short duration of the relationship), but had never had a serious girlfriend before my wife. I had just turned 29 when I moved to her country, and we met, got engaged, got married, and even got pregnant before I turned 30.
It's been a great 8 years. I think almost everyone occasionally wonder how things might have turned out if they were with someone else, but I don't think it would have been better. I don't think having a few more serious girlfriends before would have improved things, either. If anything, I wish we had both matured earlier, met earlier, and been married younger. It would have been great to go through our 20's together and skip the loneliness and heartbreaks of that long period between physical maturity and marriage.
Sustaining a healthy and happy marriage is hard even under the best conditions, and I don't think it is helped by the baggage of past relationships - especially past physical relationships.