Do you have anything prepared for this? Do you say, no but come back in a week?
Do you say, yes, here are four pre-gen character sheets, let’s play a random short one-shot?
Do you say, no we’d need to spend time prepping for D&D but here’s a simpler tabletop game which uses minis and dice, let’s play this right now instead? (for example, Shadowdark)
Or something else?
Lost Mine of Phandelver. It’s all you need to introduce them. Pre rolled characters so that amount of time is already saved and a ready-made module to run.
I’d argue the newer starter Dragons of Shipwreck Isle is a quicker and more interesting start for new players. It’s also not as long and requires a little less imagination imo since you’d probably be playing without a map