There is no single verse in the bible that tells us that first century Christians celebrated the birth of the lord jesus christ.
No. First of all it is not because there are many to celebrate Christmas makes it celebration valid or biblical Mary and Joseph where they acknowledged parents of christ when he was born in the flesh and there is no record in the bible that Mary and Joseph celebrated the birth of christ what is recorded that they are regularly going to Jerusalem celebrate the feast of the passover. Luke 2 verse 41 now parents went to Jerusalem every year at the feast of the passover.
Verse 12, And when he was twelve years old,they went up to Jerusalem after the custom of the feast.
Verse 43, and when they had fulfilled the days,as they returned the child jesus tarried behind in,Jerusalem and Joseph and his mother knew not of it.
Ecclesiastes 7 verse 1, A good name is better than previous ointment; and the day of death than the day of one's birth.