Don't count on it.
They can't tell you the weight of your baby til they have him on the scales.
Don't go for an unnecessary c/s if you don't have to.
My DD1 was born at 41+1wks, & my DD2 was 41wks.
Both my labours started naturally.
My DD1 was 7lb 5oz. I was told DD2 would be smaller.
8lb 9oz. Not even close!

Good luck.
*labour vibes*
Hope he makes his way soon.

BTW Alot of first babies go over due coz your cervix is closed tight. It has to to a little bit more work than with subsequent babies. After your first it will usually stay around 2cm open.
Your cervix may just be preparing itself right now.