Condiments will get you nowhere.
I bought marmite and vegemite when i did my groceries last night.
Gonna smash a marmite sandwich (or 3) for lunch tomorrow. (Y)
Come on, don’t walk all over this guy.
This thread is a few (key)strokes away from a triathlon
Well I think it’s going just swimmingly.
Do both.
Building bikes is frustrating and fun but its great knowing your bike inside and out.
You are going to need a heap of tools though which will add to the build cost so get riding first 
i thought the swim was first?
With all this talk of swimming and running and bikes this thread is dangerously close to a triathlon.
in which case i’d suggest that the OP steer clear of any bikes with brass seat posts to avoid potential on bike peeing related SCC failures
IITT all the pun masters lap it up
A man’s gotta have choices
compression socks
Ok guys…
But lastly what would be the first things to upgrade/adjust?
Perhaps just buy something first. Ride it, and see what needs adjusting.
If you end up with a second hand bike/OTS with 120 spacing and you think riding fixed is for you -
save for some wheels. These will be able to transfer onto whatever your next frame is.
Yeah just pick up something first, after you get a few km’s on it you’ll know what you want to do with it. No point worrying about upgrades before you know what you’ll get or what you’ll need.
Get a saddle if you need to. I find most stock ones are crap.
And get some clipless pedals. Then ride it.
And a top tube pad. It’s not a proper fixie without one!
Foot retention on your pedals. Straps or cages, whichever feels more natural. I like straps because my feet naturally turn out but to each their own. Just get some cheap BMX pedals and whatever else you can find. You might need to get a shop to change them for you if you don’t have a pedal wrench though.