The rise time is specified in Amps per microsecond. The fall time doesn't really apply since the current must go to zero for the Triac to turn-off.

Typical delay before any current flows in T1/T2:
[![enter image description here][1]][1]

Max rise time:
[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/pQefw.png
  [2]: https://i.sstatic.net/now7Z.png