It's almost closely possible to assume that if you pay the recommended fee or the median fee and that the mempool has not a lot of spam transactions in it for the miners to mine in the next block, it should probably either confirm in the very next block or 2-3 blocks after that. In general the mining hash power and the number of unconfirmed transactions in the mem pool should give you some idea of the possibility of the transaction being confirmed within the next block if you've paid the recommended fee.

When there are a lot of transactions to confirm, then probably the fee increases and you may have to replace-by-fee or utilize the child pays for parent feature in your wallet to bump up the fees if needed, to have it confirmed in the next block or within 2-3 blocks.