The twenty three years of my marriage thus far seem to have gone by so very quickly. Perhaps I got lucky when meeting my wife, but I like to think that choosing the smartest woman that would have me figures into our happiness. Choose your mate wisely, and then choose them every day after.
I believe you become married the moment your partner agrees to marry you. Not when you get the marriage license, or after the ceremony, but when the both of you agree. If you think that you need the blessing of some institution before you can behave like a married couple you have abdicated the responsibility for your choice for perhaps the most important plot arc of your life.
An engagement only gives your friends and family time to make travel arrangements. Celebrate your marriage in whatever way you choose, but celebrate the done deal and not the doing.
These two bits of my father's wisdom, dealing nominally with finance and footwear, I hope you find as broadly applicable as I:
"There's no such thing as a tube stock. One size does not fit all."
"There are only two sizes of shoe: fit and don't-fit."
Alvin, Texas, USA