I thought I had written this, but I couldn't find it. So here it is, the extreme Baptists have tried to force upon us that baptism by sprinkling was a later mode, in 2nd or 3rd century, though there's no clear evidence in what mode was used in the early church. They are correlating cases where in 2, 3rd century, there are heretical views of trying to save babies, etc. by baptism and hence they invented sprinkling, etc. Those cannot be reason to generalize the entire history of how sprinkling comes about.
I saw in Metropolitan Museum of Arts once that Baptizo was long understood as even sprinkling by the Egyptian in the first century, A.D. 41–68 to be exact:
This block originally formed part of a screen wall that connected the four front columns and the sidewalls of the temple of Harendotes ("Horus the Avenger") on the island of Philae. The relief represents the "Baptism of Pharaoh," a purification ritual that was part of Egyptian coronation ceremonies. The gods Horus (not preserved) and the ibis-headed Thoth poured water-here represented by streams of ankh (life) and was (dominion) hieroglyphs-over the head of the king. The pharaoh whose head is partially preserved is a Claudian emperor, most probably either Claudius or Nero.
This is not about comparing Christianity with Pagan religion, but about how the word baptizo was understood in as original as possible the proper language, time, culture and context; which is what the proponent of submersion baptism kept using to support their claim. Egypt would be rather Hellenistic by then, so I THINK, the Greek word baptizo is linked to the piece of art above. I have not done further investigation on it, but I am satisfied about it for now. If I could, I would ask the curator on this where the get the word/idea of "baptism" from this carving.
On confronting this debate, I would just settle with unknown. I go with sprinkler because of the closest cultural reference above.