Set the SLA by source, not one number for everything. A demo request and a cold list upload are not the same commitment — higher-intent sources get tighter response windows and sometimes their own team. Then instrument the handoff so the SLA is measured, not assumed.
The number matters less than the instrumentation. Most teams cannot answer "what was our median time-to-first-touch by source last month?" because the handoff was never timestamped. Track the original source through routing, stamp assignment and first activity, and the SLA becomes a managed metric rather than a slogan.
Every claim above comes from work LeanScale published. These are the sources.