As best I can remember, there is no existing evidence of any belief in the assumption until centuries after the apostles.
Was there a belief that pre-dates the evidence? Yeah…probably but you guys have no way of tracing it back to the apostles (as best I can tell).
As mentioned before, there may be some hope for you to do that based on a early date for the feast of the assumption but from what little I have looked into that, there is quite a bit of confusion as to what the early Marian feasts actually were celebrating.
I believe newadvent.org points out that what some historians/apologists take as being early evidence for being a feast of the assumption was actually a feast of the dormition.
I haven’t studied this part out in any detail so right now, I have no solid opinion as to when the first feast of the assumption took place.