The amount of time it will take for bitcoin to appear in your Bitkey wallet will vary based on the exchange you are sending from. Some exchanges will process transactions immediately, allowing you to see the bitcoin in your Bitkey wallet almost instantly. However, other exchanges may batch transactions over the course of an hour or a day. If this happens, you bitcoin won't be visible in your Bitkey wallet until the transaction is visible on the mempool. This is why it's important to check with the exchange you use to understand their specific processing times and policies.