Once accepted you will see in 15 minutes the time it takes for them to mine their next block (sometimes 2) that there's already a confirmation on the tx id you submitted.
There... fixed that for you. 
There isn't a guaranteed "15 minutes"... I've seen stretches where ViaBTC don't mine a block for up to 6 hours or more... if they don't mine a block, there is no way for them to include your transaction!
Currently, they have about 1/9th of the total hashrate... so expect them to find about 10-15 blocks a day... or around one every 1-2 hours on average.... assuming of course that their percentage of the total hashrate doesn't change (and making allowances for variance and "luck"
)