I just made a transaction from my Poloniex account to my Stellar account.
How many confirmations (and minutes) should occur so i'ii receive the coins in my Stellar account?
usually instant. but some exchange will keep for few minutes to complete.
Apparently there is a problem withdrawing stellar from Poloniex to personal Stellar accounts.
Poloniex mention that there was an error regarding the transaction, without crediting my account.
After more than 9 hours I've finally received my coins.