This was before space age but I believe you can start with a max size starting area and nerf pollution spreading so you never deal with biters and only focus on production. Also increasing the size and richness of the ore patches helps so you never need to touch trains. I’ve also completed two vanilla runs and got significantly through Bob’s and Angel’s mods before attempting this.

With this I was able to launch a rocket in 6h52m on my first try.

Here are my steps:

1. Make your basic furnace stacks, the start of a bus, and starter production of infrastructure (belts, inserters, etc.)
2. Get oil and build in anticipation of advanced oil processing. Put fluid lines in their own bus lanes. Set up red circuits and blue science.
3. Rush bots, but not much more than personal construction bots and perhaps a few logistics bots, but not more than a few. Use them for solar power. Nuclear is not necessary.
4. Beeline for the rocket. Don’t research unnecessary things. Build what’s enough and don’t plan for megabase expandability. Hopefully this will achieve the achievement.

I haven’t done the new space age timed run achievements yet. I still consider the timed runs to be 15hrs and 8hr… lol.

Much of the same rules apply im guessing: Adjust resource settings to be higher density, pre-blueprint a lot of stuff, bum-rush construction robots as fast as humanly possible. Build wide with low teir belts/machines, don’t bother with optimizing, modulizing, or investing your limited resources into higher level belts or machines.
Also, your character crafting queue should NEVER be idle. You should always be making some kind of construction material, or if you don’t need that, then science packs. It helps.

If you don’t care about doing it “yourself” there are guides you can follow that give you a seed and set of blueprints. These can pretty safely get you under 10 hours. Some say 5 but you won’t be perfect.

I got down to about 20 hours myself then just used a guide for the achievement.