Since the rules mention "Time will begin upon completion of the loading period after pressing "Start"." Would it be okay to save a game and load it at the spot he spawns at? If so, are there any downsides to this?

Yeah you can do this, but I believe it takes 0.36s for your character to drop down to the ground after Level 1 loads (he spawns in the air) so you'll have to add 0.36s to your time.

First of all it is ok to do this. the only downside is as this game seems to run slightly faster or slower depending on the computer the time it can take to fall to the ground can be about 0.17s to 0.21s

Just add 0.20s to your run if you use this.