Basic Expert
Explorer
For 5e, I'd say 3-4 sessions of about 4 hours. Add a session or two if the scenario has heavier roleplaying or requires additional exposition to set up campaign detail.
Levels 1-2 in 5e are generally training-wheel levels and can easily be skipped. They are most useful to allow new players to learn the basics and to give a complete "zero to hero" arc.
I generally favor starting at 3rd now. The PCs are far more resilient, can handle more challenges, and have much needed crit resistance to allow for far more dynamic gameplay (even outside of expanded class features). Bumbling inchoate heroes don't do much for me.
Levels 1-2 in 5e are generally training-wheel levels and can easily be skipped. They are most useful to allow new players to learn the basics and to give a complete "zero to hero" arc.
I generally favor starting at 3rd now. The PCs are far more resilient, can handle more challenges, and have much needed crit resistance to allow for far more dynamic gameplay (even outside of expanded class features). Bumbling inchoate heroes don't do much for me.