# Profit-Check - what does a new customer really cost you? with Rafael Gaviria Meza

> A free 30-minute video call. Together we calculate CAC and contribution margin for your top 3 channels, live with your own numbers. Bring whatever you have: Revenue and ad spend per channel Number of new customers Average order value and margin Shipping, returns and discounts Repeat purchase rate Missing numbers? No problem, we'll work with estimates. You leave with 3 quick wins, plus a short written summary afterwards. No obligation. Who should join: whoever runs marketing. If a founder or someone from finance can join too, even better. Best suited for: D2C and consumer brands already spending €20K+ a month on ads. Your numbers stay confidential, and I'm happy to sign an NDA beforehand. The call can be in English or German.

- Host: Rafael Gaviria Meza
- Duration: 30 min
- Location: Google Meet
- Host time zone: Europe/Berlin
- Confirmation: Bookings are confirmed instantly.
- Booking page: https://cal.com/rafael-gaviria-ujzfoj/profit-check
- Event type id: 7679724

## Check availability

```http
GET https://api.cal.com/v2/slots?eventTypeId=7679724&start=YYYY-MM-DD&end=YYYY-MM-DD&timeZone=<IANA time zone>
cal-api-version: 2024-09-04
```

The response is `{"data":{"YYYY-MM-DD":[{"start":"<ISO 8601 with offset>"}]}}`; no API key is needed.

## Book

```http
POST https://api.cal.com/v2/bookings
cal-api-version: 2026-02-25
Content-Type: application/json

{
  "eventTypeId": 7679724,
  "start": "<UTC ISO 8601 start from the slots response>",
  "attendee": {
    "name": "…",
    "email": "…",
    "timeZone": "<IANA time zone>"
  },
  "guests": [
    "guest@example.com"
  ],
  "bookingFieldsResponses": {
    "attendeePhoneNumber": "…",
    "Website": "…",
    "Monthly-ad-spend": "…",
    "Top-3-channels-by-ad-spend": "…",
    "Other-channels": "…",
    "notes": "…"
  }
}
```

- Required fields: `name` (Your name), `email` (Email address), `attendeePhoneNumber` (Phone number), `Website` (Website), `Monthly-ad-spend` (Monthly ad spend), `Top-3-channels-by-ad-spend` (Top 3 channels by ad spend)
- Optional fields: `Other-channels` (Other channels), `notes` (Additional notes), `guests` (Add guests)
- `name` and `email` go in `attendee` and `guests` is a list of emails; every other field goes in `bookingFieldsResponses` under its name.