I think that depends on where you sent the deposit from. I think most exchanges should only take a couple hours to send it over.  Check the exchange to make sure they really sent it (if they give you a transaction ID then check block explorer to confirm ( https://www.coinexplorer.net/EMB ).  

If blockexplorer shows it is confirmed a bunch of times, but it still shows in "pending deposits" in stakeunited, then maybe you entered the wrong info in stakeunited.  Click "support" on stakeunited and open a new ticket.  Give them the coin, the amount, and the transaction id and they should be able to figure it out.  If you entered the info correctly, your deposits should move from "Pending Deposits" to "Deposit History" in less than 2 hours...it all depends on how long confirmations take on that coin's network....but usually you should see the deposit move in 30 minutes or so.

If stakeunited shows your deposit in the "deposit history" and there is a red circle icon there, then the deposit went through and you are just waiting to join the next stake.  Once it's green then you should have recieved a stake, check your stake history.   The first stake ususally takes 24-48 hours to get.  This is due to the way they do coin control to maximize profits.  Yeah, it takes a while, but once you are in then you are golden.  That first stake is always brutal waiting.

They are super helpful on their discord, and you can always ping me in there if you need to (@LotCooler).