Stuck here, need advice

So my merit position for the Business NET is 276, that means I will definitely get admission in the field I desire (Public Administration).

I am also a candidate for commission in PAF. I have already cleared every single thing (ISSB, CMB, FAT) etc. I am only waiting for the joining letter as of right now. The thing about joining letters is that, since the seats in GDP branch are very limited, I am still unsure whether or not I will make it or not (about 35-40 seats in the GDP branch).

The main issue is that I don't wanna miss my chance of going to NUST incase I get low merit in the PAF and I don't want to take a gap year. I don't know what the deadline of securing your seat in NUST is. Furthermore, I also don't want almost 3 lacs going to waste incase I do get selected. Is there any way, they can delay my joining in classes or something? Because the PAF joining letters will be issued in mid of september and by that time, classes have already started.

So, what should I do, go to NUST and meet the Head of Admissions? This is the only option I can think of that is feasible because NUST is close to where I live.

Could use some advice.