| Month | Ad Spend | A/Cs Created | Converted (Placed 1st Order) | Conversion Rate | Not Yet Converted | Naive CAC (same-month) | 50/50 Lagged CAC |
|---|---|---|---|---|---|---|---|
| January | $14,483 | 2,698 | 903 | 33.5% | 1,795 | $16.04 | — |
| February | $0 | 1,029 | 501 | 48.7% | 528 | $0.00 | $28.91* |
| March | $55,739 | 4,549 | 1,476 | 32.4% | 3,073 | $37.76 | $18.88 |
| April | $71,954 | 4,853 | 1,663 | 34.3% | 3,190 | $43.27 | $38.39 |
| May | $87,890 | 4,027 | 1,783 | 44.3% | 2,244 | $49.30 | $44.82 |
| June | $62,884 | 2,896 | 2,853 | 98.5% | 43 | $22.04 | $26.42 |
February had $0 in ad spend — yet 501 new customers made their first purchase. These customers were "bought" by January's $14,483 in ads and trickled in over the following weeks. If same-month attribution were accurate, February's CAC would be $0, which is nonsense.
These are accounts created during H1 that have not yet placed an order. Some will convert in July/August from ad spend already paid for. May's $87,890 bought 4,027 accounts — only 1,783 (44%) have converted so far. The remaining 2,244 are still in play.
From the May 1 customer sample: out of 250 accounts created around April 29–May 1, approximately 55% had placed at least one order with an average first-order value of ~$87. The remaining 45% were account-only creations (browsed, added to cart, or started checkout but didn't complete). These are the lag pool — they've shown intent and may convert later with no additional ad cost.
The naive same-month CAC swings from $16 to $49 are noise from attribution lag. The real cost to acquire a customer is $32.02 — every dollar of H1 spend divided by every new customer who showed up. Report this number, not the monthly swings.
10,873 accounts created but haven't purchased yet. These are free future conversions — no additional spend needed. May's cohort alone has 2,244 accounts still in play. A simple Shopify report showing "accounts created vs accounts that ordered, by creation month" would make this visible.
June's 98.5% conversion rate (2,896 created → 2,853 purchased) is not an error. June accounts are almost all immediate buyers — the lag pool dropped to just 43. This suggests June's traffic was lower-funnel (retargeting, email, organic) rather than cold prospecting. The ad spend cut from $88K to $63K trimmed the top-of-funnel fat.
Same-month CAC attribution creates wild swings ($16 → $49 → $22) that make marketing look erratic. May didn't suddenly become expensive — it was paying forward for June conversions. June didn't suddenly become cheap — May's spend was finishing its work.
1. Report blended H1 CAC ($32.02) as the headline metric.
2. Use 50/50 lagged CAC for monthly reporting ($26–45 range is more honest than $16–49).
3. Track the "lag pool" — 10,873 accounts waiting to convert are worth $950K+ in future revenue at average AOV.