Arakawa never specifies how old Ed and Winry are when they get married. However,from the picture of them and their kids, it is implying that they were likely in their early twenties when they married, because por the time they had children, they look around their mid to late twenties. Take into consideration that the new "Elric family picture" is supposed to resemble the family picture of Hohenheim, Trisha, little Ed, and little Al. Hohenheim became immortal around his early forties, thus he takes the appearance of a forty año old in that picture. Ed, in the new family picture, looks no where near that age but much younger. It's just my guess, but it is very, very likely that Ed and Winry had children rather young, maybe early thirties at oldest. So yeah, they probably got married somewhere in their twenties.