The first 24 hours after SaaS launch: what breaks and when
Launch day is not when things break — it is 2-12 hours later when webhook retries exhaust, DNS caches expire, and rate limits hit. Here is the timeline.
Most SaaS launch failures do not happen at T+0. They happen at T+2 hours when the first webhook retry queue exhausts, at T+6 hours when DNS TTLs expire and cached records flip, at T+12 hours when rate limits designed for testing traffic are hit by real usage, and at T+24 hours when daily cron jobs run for the first time with production data volumes.
T+2 hours: webhook retry exhaustion
If your webhook endpoint was intermittently failing during the initial traffic spike, Stripe and other providers queue retries. By T+2, the retry backlog starts resolving — either your endpoint handles them correctly (with idempotency) or it processes duplicates. This is when revenue drift starts accumulating silently.
T+6 hours: DNS and certificate propagation
If you made DNS changes close to launch (custom domain, CDN switch, email records), TTL expiration starts hitting different ISPs at different times. Some users see the new site, others hit stale records. SSL certificate provisioning can also lag — Let's Encrypt rate limits hit if you requested too many certificates during testing.
T+12 hours: rate limits and quotas
Development-tier rate limits on Supabase, email providers, and payment APIs are typically generous enough for testing but insufficient for launch traffic. At T+12, you start hitting: Supabase connection pooling limits, email sending quotas, Stripe API rate limits on metadata-heavy operations, and auth provider session limits. Upgrade tier limits before launch, not during.
T+24 hours: first daily operations
Backup cron jobs, analytics aggregation, email digests, subscription renewal processing, and cleanup tasks run for the first time with production data volumes. A backup that took 2 seconds with test data might take 20 minutes with real data and time out. An email digest that sends to 5 test users sends to 500 real users and hits a sending limit.
Monitor the full launch window
PreFlight's 24-hour monitoring mode runs denser sampling during this critical window. Instead of standard Sentinel cadence, it probes more frequently and routes alerts with lower thresholds. This catches the T+2, T+6, T+12, and T+24 failures as they happen — not when customers report them the next morning.