The platforms’ algorithms are extremely effective at finding more of whatever you tell them is success. When that’s 'free trial signup,' they find users who love free things — including users who will never pay. When it’s 'New Customer with $X value,' they find users who buy.
Volume threshold
Meta and Google both need at least 50 conversions per week to optimize reliably on a deeper-funnel event. If your weekly New Customer volume is below that, optimize on the closest deeper event you do have volume for (often Trial Converted) and use New Customer as a secondary signal.
Pair the New Customer event with a value parameter — typically the first month’s MRR or expected LTV — so the platform can run value-based bidding instead of pure conversion bidding.
- Above 50 weekly New Customers → optimize on New Customer with value bidding
- 20–50 weekly Trial Converted → optimize on Trial Converted, push New Customer for retargeting
- Below 20 weekly Trial Converted → optimize on Trial Started, push deeper events for audience enrichment
Expected patterns
When you switch the optimization event from Trial Started to New Customer, expect cost-per-trial to roughly double and trial volume to drop 30–60%. That’s the algorithm doing its job — finding higher-intent users.
The number that should improve is cost-per-customer or LTV ROAS. If you don’t see improvement in 6–8 weeks, the issue is usually creative-audience fit, not the optimization event.
What to watch for.
- Switching events without enough volume
Below 50 weekly conversions the algorithm can’t learn. Stay on the higher-volume event.
- Cutting the trial event entirely
Keep the trial event live as a secondary signal for retargeting and lookalikes. Just don’t optimize on it.
- Not sending value with the New Customer event
Without a value parameter, the platforms can’t do value-based bidding. Always pass first-month MRR or expected LTV.
Recap.
- Push New Customer events to Meta, Google, LinkedIn, TikTok, and Bing simultaneously
- Wait for at least 50 New Customer events per week before switching the optimization event
- Pair the New Customer optimization event with a value parameter to enable ROAS bidding
- Expect CPL and trial volume to drop and paying-customer volume to rise — that’s the goal
- Keep the trial event live as a secondary signal for retargeting and lookalike audiences