When to trigger on injection?

[megavar]

Hi guys,

I currently have a 2D with DDS3 set to turn on at 12psi (minimum) and is injecting 75:25 meth to water. The car has a peak boost of 26psi so the injection is on a fair bit of the time. I seem to remember reading that it is better to activate the WI much closer to the peak boost (and I doubt whether it is necesary below 18-20 psi on my vehicle). Would this early onset be slowing boost rise or causing any other negative effects beside additional meth/water consumption?
Your input would be appreciated.
cheers

Matt