If Boo woke up at less than full power...

[SSJ2]

Would things have turned out the same? Do you think he'd still have access to his full power that he later displayed?

 

[GSM123]

He'd wake up as strong as SSJ2 Gohan because Boo is <1/2 SSJ3 Goku

But seriously, i don't think he'd manage to wake up at all. That energy he collected is like the energy needed to jumpstart a car, for example.

 

[SSJ2]

Babidi and Kaioshin both seem to imply that he would awaken though. I don't think those statements would be included for no reason..

 

[Captain Cadaver]

You could assume their expectations were wrong and just there to provide some conflicting opinions in-universe.

Assuming he would awaken early, I expect how much power he could access would correlate with the energy provided. For instance, assuming he woke up at half the necessary energy, he'd likely only be able to access half of his full power. Whether or not this would impact the plot much would depend on whether or not he gets angry enough to split and eventually become Evil Boo far earlier or at what percentage/time period he was awoken.

 

[withheldforprivacy]

I think Fat Buu was eventually able to access his full power (Super Buu).
With less energy, he'd have started at less than he started in canon
(~SSJ2 Kid Gohan) and it would take him longer to access his max.