It all depends on local supply too.
Take the offer up, you might as well.
They're wanting to get as many people fully done as quickly as possible.
If you do it now, you won't have to isolate come August 16th either (unless you have it).
What's there to lose?
When you booked online, was your spacing 12 or 8 weeks? If you go back on now, you'd be able to move it down to 8 weeks.
8 weeks. If it was originally medically/scientifically recommended to space them 8 weeks then I’m not getting it any sooner than 8 weeks.