I am building an entirely new PC, with the 3080 Ti FTW3 Ultra. I might be able to get away with a lower amount, but I assumed 1000w would be safer, especially if I overclock the Intel Core i7 12700K and the GPU. 
How often should you upgrade the power supply? I don't exactly know what 'signs' to look out for on an aging PSU. I guessed that the sign would be the PC not turning on, which is currently not the case. 
If I can definitely keep using my current PSU that'll save me about $180.
Appreciate any answers!

Sajin
Install it with your new parts, and then run the occt power supply test. If the system doesn't shutdown you could still continue to use it, but I wouldn't since the unit may be giving out higher than normal ripple which could damage/shorten the lifespan of your hardware. I would get a new psu when getting new hardware just to be safe.

Yeah, I'm thinking to hell with it and just upgrading it. This new PC will last me another 5-7 years, and I don't want a 10+ year old PSU. I am looking at a Seasonic Prime 1000w, Titanium-rated, looks pretty good. I need to determine the best site to guesstimate how much watts I need. I've seen a 1300w Seasonic being used in a video that used the same CPU and GPU, so maybe I need more.

I have a G2 1300w that is 6 years old and a P2 1600w that is 5 years old.  Both have been in constant use since the day I got them.

My vote is put that bad boy in your new system and carry on.   These Super Flower PSU's are tough and resilient and some of the best power supplies I have ever had the pleasure of using.

A follow-up to this. I decided to keep using the Supernova P2 1200w Platinum PSU. I was even able to still register it, so it has around 4 years of warranty left. So, it seems like upgrading at the moment would be silly. I'll stick with this and keep an eye out for any issues. Although I heard that most issues are typically your pc not posting lol. EVGA made everything easy