Fronts!
Fronts/threats/portents are just an organization tool (plus some inspiration, I guess) for your prep.
You don't need to worry about them at all until after the first session, and even then, they're more... there if you need them.
(In 20+ sessions of DW, I think I've used fronts... twice?)
The most important thing to get down is the flow of play, the moves, asking questions, interacting with the players.
But, once you know the rules (move structure, basic moves, flow of play, some peripheral stuff, damage and healing), just present an interesting, exciting, dangerous situation to your players and go from there.
And then, use fronts if you want them, if you think it'll help. But, don't let them get in your way.
Oh, but, if you have some questions about fronts or want to learn more, do feel free to ask. I mean, not me, I don't really know them well and don't really use them, but I bet someone here can help. :)
- Alex