Every new ad group goes through a learning phase: the system tests delivery across different audiences to find who responds best. It typically lasts until the group reaches about 50 conversions.
During learning, cost per conversion can run 30–50% above its stable level and swing day to day. This is normal behavior, not a sign of failure.
Do: keep the configuration unchanged for at least 3–5 days; make sure budget supports ~10 conversions per day; bring quality creative from the start, since early signals strongly shape the learning direction.
Don't: keep tweaking audience, bid, or budget (each major edit restarts learning); kill a group after only 1–2 days; run too many groups on small budgets so none accumulates enough data.
Once the group exits learning and stabilizes, that is the time to scale budget in small steps, as covered in our budget management guide.