While it only takes up to 30 seconds for transactions to be confirmed on the NavCoin blockchain, after receiving your coins exchanges need to update your records in their system.
Some exchanges like to wait longer than others before updating your balance and other factors such as having a new account might also affect the time it takes for your funds to be confirmed by their system.
Similar to the above, some exchanges can take quite a while before sending coins, this can be affected by factors such as having a new account. In 99% of cases all you need to do is wait for the coins to come through, however if you have concerns that something has gone wrong it is reccomended to contact the exchagne directly.