What are some things that would be so much better if they happened sooner rather than later? Like things that waiting the full amount of time for is so agonizing that everyone wishes it could just happen sooner? This might sound easy but I need the right things and I just can't think of them. Please, help me.
Software bugs in safety critical systems. Catch them early and you can fix it before hundreds of people die. This used to be my job and it felt horrible no matter how many times I checked everything. I stared at the screen for years looking at the test videos playing over and over, trying to find a hint of defects in the robotic vision as the planes took off and landed. Still, I knew that nobody else could do it better than me within the customer's budget, and missing the deadline would mean using an even older system, which in turn was safer than relying on humans only.
Something your protagonist dreads happening but he knows will happen. I once waited more than half a year for a new job to start while not wanting to leave the old one. The wait was not comfortable. I'd rather got it done and over with.
Failing romantic relationships. When you know they're going to end in pain, just rip the Band-aid off, already.
Could do with some context. There are a billion things -- converting a hot date to a night of passion, a pint of lager on a warm day, the first try in an England rugby match, Brexit...
Waiting for test results when the doctor knows you have a serious illness but isn't sure if it's the curable one or the one that will kill you (happened to a friend).
Waiting for important test results, period. It's not fun. Everything just goes into stasis because you can't plan anything, really. Never mind the worry as well.