Buyer offering on the spot BACS transfer, safe to accept?

[singlecoil]

I'm selling some equipment for £4,000. A potential buyer is offering to put through a BACS transfer on his phone after looking at the stuff. If it shows up in my account shortly afterwards is it safe for me to accept? I did Google this but the advice seems to be to not send goods until the next day. In my case the buyer would want to take the goods with him.