Is delay allowed?

[aasi888]

I'm wondering if I can do this on a single key press:

keydown (Master):

/startattack
/cast Spell

keyup (Slaves):

/assist Master
/cast Heroic Strike
USE IWT hotkey

Is this allowed and is this how ISBoxer does this? IWT + Cast is done at the same time? I couldn't find anything in the docs: http://isboxer.com/wiki/WoW:Interact_with_Target

EDIT: Specifically I want to know if the key-up action you can see up here is OK (or do I need to separate the IWT from it).