Can you describe exactly what you tried to do? I'm fairly new here but I'll try to help.
- where were you buying/sending the SBD from
2.were you sending it to your steemit wallet?
As for the transaction time any time I have sent steem or SBD to my steemit wallet from an exchange it takes under 3 min to appear in my wallet, when I have bought steem using blocktrades it appeared pretty much instantly so if you did a transaction and it hasnt shown up something must be wrong.
If you tell me where the SBD is coming from I might have more answers.