What kind of delay are you talking about? Tested it and didn't find any issues, but I might be doing it wrong

This was reported only for player versus player.
When using a spec attack it does the next attack (regular attack) in the same tick as the special attack.

So if you'd have spec a 15 and the next hit would be a 12 then in the same tick you do the special attack it'd hit for 27.

NPCs: The timing works as intended

PVP: Does the special attack while and only during the next attack.