When should a startup hire its first SDR?

Hire your first SDR only once the system they will execute already exists. The honest test: you have personally closed deals in this ICP, your ICP is documented, you have a sequence that has booked meetings in the last 90 days, you have repeatable sourcing, and your sending infrastructure is warmed.

If you cannot answer yes to all of those, you are paying someone £55–75k a year to discover problems better targeting and copy would have solved for free. Most founders hire a year too early.

When you are genuinely ready — turning down meetings because you are out of hours — hire two SDRs at once, not one. A single SDR is fragile; two create a baseline you can tune around.