Ditto. AAoA can be impacted, but also you'll always have a new account ding once it reports. Most folks are limited to an impact of 6-12 months and any score drop will rebound by then.

FICO doesn't really reward you for on-time payments. You'll see gains over time due to the aging of the TL, but those aren't due to paying on-time. Conversely, paying late will drop your score in a hurry.

An auto loan is scored as an installment loan and adding one won't help your mix because you have SLs reporting.