I think it's appropriate to be very explicit. Call out the issue. Tell them you aren't signalling. Tell them you really mean what you say, and that if they're going to get burned out from that, then your shop isn't the place for them.
I think based on your responses you have the right attitude.
You nailed it. The problem is that even when being explicit in expectations, candidates will still try to get that offer, even if it's not the right fit at that time. It's really hard to tell if someone means it when they say "oh, that's fine." I think startups have a certain glamour that masks the reality and people see interviews as tests, not conversations.
Further, I'd love to keep that person in the pipeline -- employee happiness and feeling valued is huge for me, so if that person needs to come in at 10 because they need to drop a kid off at school, I can respect that, and hope he/she is available when we can accommodate it.
> I think based on your responses you have the right attitude.
I really appreciate you saying this.
Dead honest. I mean a quick async-okay-if-from-phone "hey, here's what I have lined up for this week, can you tell me if this is unreasonable from your perspective" exchange.