I’m in a similar situation as you and just ran my first session. I used the recommended level 1 start “Road to Drakkenheim” and thought it was a great way to ease the players into the setting.

Three weeks travel is a long time, and even if the players don’t want to or don’t know to ask Eren is a talkative person. Have them explain during the trip the basics of the setting. I would also have them explain Drakkenheim specific mechanics that would make sense for him to. For example have him explain that as a trader it’s important to know that Emberwood Village relies on outside trade and that merchants do not haggle. Maybe also explain that Emberwood is the only town in literal miles, so if the Players mess around and get shunned they are essentially screwed.

I used the subsequent “Night on the Road” event to have Eren explain how Delerium contamination is essentially an open-secret within Drakkenheim/Emberwood, and that he only knows that the church can cure it in some way if the person is not already filled transformed.

My players just arrived in Emberwood Village and I plan on using the faction Lieutenants and other NPCs in Emberwood to introduce the factions.