Prague has two passenger terminals next to each other. Terminal 1 handles flights from outside the Schengen area — the UK, Ireland, the US, the Middle East and Asia, for example — so you'll go through passport control before baggage claim. Terminal 2 handles flights from Schengen countries, with no passport check on arrival. Either way, allow around 15–40 minutes from landing to the arrivals hall, depending on queues and how quickly bags arrive.
Your driver already knows your flight and waits in the arrivals hall with a sign showing your name: in Terminal 1 by the Mattoni bar on your left as you come out, and in Terminal 2 by the information centre just outside the arrivals hall. See the meeting point guide for directions. If your bags are delayed or lost, report it at the airline's baggage desk before you leave the baggage hall, then message us on WhatsApp — your driver will wait.
A tip on money: the Czech Republic uses the Czech koruna (CZK), and cards are accepted almost everywhere. If you want cash, use a bank ATM rather than an exchange booth, and if a card machine or ATM offers to charge you in your home currency, choose CZK — the conversion offered is usually worse. Your transfer is already paid when you book, so there's nothing to pay the driver.