The JAR-OPS 1.495 specified no track changes below half the wingspan (56 feet on a A320) and above this to 400 feet you could bank a maximum of 15 degrees AOB.
A320 specifically- As the flight guidance part will limit your bank angle to 15 degrees AOB ,at typical take off speeds,and you have a track change of 15 degrees its acceptable to make the turn before 400 AGL just not below 56 feet ever.
Page 65 and 66 on the document "Getting to grips with aircraft performance" which STARBEAR posted a link to is the reference.