TL;DR (Short Answer)
Rewards start after your stake is Active for a full epoch.
Solana epochs ≈ 2 days.
If you deposit mid-epoch, you won't earn for that epoch. Your first rewards appear right after the next full Active epoch ends (auto-compounded).
How it works
Deposit → stake shows Initialized/Activating (not earning).
Start of the next epoch → stake becomes Active.
Stay Active for the full epoch → you earn for that epoch.
After the epoch ends → rewards are credited automatically and auto-compounded.
Status Glossary
Initialized: Account created; queued to turn Active at the start of the next epoch.
Active: Eligible to earn; rewards post after the epoch ends.
Inactive (re-delegation): Temporary during Marinade reallocation; no action needed.
If you unstake this portion, it's available immediately.
Example Timeline
Epoch X: Deposit mid-epoch → Activating → no rewards for X.
Epoch X+1: Active for the entire epoch → you earn for X+1.
Start of Epoch X+2: Rewards for X+1 appear (auto-compounded).
If an Epoch Has Passed and You Still See Nothing
Marinade Native moves stake between validators every epoch to keep you with validators that are performing well. Newly moved stake has to activate again before it earns, and a position under 2 SOL has to move as a whole block, since Solana requires a minimum of 1 SOL per stake account. That can push your first reward out by more than one epoch.
Full explanation: I Deposited But Have No Rewards Yet
FAQ
Do I need to claim?
No. Auto-compound is built in.
How long is an epoch?
About 2 days. Timing can vary slightly.
Why do I see "Inactive"?
This can happen during short re-delegation by Marinade and is normal and temporary. See the guide: Understanding inactive validators in Marinade staking.