Hi Ann,
The first who started using the label “Baptist” date from about the 1600s.
Those, however, who practiced immersion baptism and credo baptism date from a much earlier period. Those are the 2 major items of their “baptism” doctrine, and immersion baptism definitely is as old as Eastern Orthodoxy, and credo-baptism is also very early.
So, the label wasn’t used early, but the major baptism practices were.
Baptism is from the year 32 or 33 from John the Baptist, Jesus’s cousin.