I disagree with the entire premise of the question. I would not try to steer someone, especially a young someone, into any of these directions. I would discuss all of them (as we plan to do with our daughter before she becomes sexually active) and let her know that choice is hers and hers alone.
Importantly, you don't have to choose a single path. A person can start down one path, like the one option proposed, seeking and being monogamous then swinging. You can also go the other way, as many do, having a multiple-partner, non-monogamous life, then settling into a monogamous marriage. Then maybe swinging again after a while. Or not.
My two wives show this. After only a few partners each (nothing wild), my first wife Betsy and I were monogamous for twenty years of marriage. We had a great sex life, even during and after the divorce for a while.
My wife now Daniela who is twenty-five years younger than me has had many partners of both sexes, overlapping lovers, married lovers, etc. That is the life that she chose and it's worked out wonderfully.
We were monogamous for a short while, until I recognized that she missed the sexual variety and quantity that she used to have, so she played and I stayed monogamous. Then she wanted me involved (MFM), then we did couples swaps, until now we are in a closed group of married couples.
My ex-wife knows that Daniela and I swing, and we three have talked about whether Betsy and I should have talked about it and explored when we were married.
To summarize: yes, talk honestly about all of the possibilities, don't put one above the other, and tell him or her that your feelings and attitude will likely change, perhaps more than once. Most importantly, be safe. Not just the usual things, but also your emotions. The first, second, tenth person that you date and fuck may make you feel crazy, but be realistic.