Could Ph Shock slow down a plants flowering?

???

Good question.
Probably not. But it WILL hurt yield if it's in a poor pH for any significant length of time, and you COULD force hermis.
Things that affect LENGTH of flower time are genetics and heat/co2 (I lump those together because when you crank up temps, you have to add CO2 to keep the plants healthy)- more heat = couple days off flower time.
Oh! Light leaks slow it down too. Almost forgot.

thank you mrs stinky!