We named our sons common, but long, names which both tend toward nicknames. We never used a short form.
One boy picked up an unusual, Greek variation as a nickname. He was old enough to express a preference, around age four, so we stuck with it.
The other boy did not like any of the nicknames, OR his proper name. As a teen, he started asking us to call him by his middle name. It took me about two years to re-train the habit, but it also took me about the same amount of time to remember a female friend's new married surname.
So, save yourself a whole lot of family friction and TRY to get used to the new nickname. Have a frank but hopeful talk about WHY you chose the name you did, and ask if he minds if YOU continue to call him Andrew. That took the pressure down a bit for about a year, and then I was the only holdout, so I made serious effort to use the new name.
Names
One boy picked up an unusual, Greek variation as a nickname. He was old enough to express a preference, around age four, so we stuck with it.
The other boy did not like any of the nicknames, OR his proper name. As a teen, he started asking us to call him by his middle name. It took me about two years to re-train the habit, but it also took me about the same amount of time to remember a female friend's new married surname.
So, save yourself a whole lot of family friction and TRY to get used to the new nickname. Have a frank but hopeful talk about WHY you chose the name you did, and ask if he minds if YOU continue to call him Andrew. That took the pressure down a bit for about a year, and then I was the only holdout, so I made serious effort to use the new name.