How soon is too soon to be exchanging numbers on a dating app?

It’s been 2 days of chatting back and forth, but this one guy recommended moving to another app like whatsapp. I feel it’s too soon, so I suggested other forms of social media first, but he insisted he is more active there. What do you think is the right thing to do?
Updates
8 mo
He apologised for asking and said whatever you’re comfortable with. Seems sweet, I’ll give it a few more days and then decide.
How soon is too soon to be exchanging numbers on a dating app?
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