So hypothetically if I were to start a new game from scratch, when should I first start a colony? When I have $3 mil and at least two capital ships with 50+ fleet?
Your colony will produce that about, what, 20 times over in the time it takes to go from size 4 to size 5?
First colony is when you have 3+ alpha's and a pristine nanoforge. If you don't have tech invested in a colony then just let the events play out. What's the worst that's going to happen, you'll lose a colony that in your own words, isn't making any money? Colonies are something you make after you've already been farming remnants, though it's true this is less clearly communicated than it was when you needed an alpha to govern it.
So tell me the right meta to play this game.
Far from the best method but the most straightforward is to just get a tri-tach commission and buy ships from their blackmarket and military commission. This gives you a monthly income and cash rewards for killing nerds (or nerd abusers, I guess, technically) without adding any sort of liability. Heg are less auto-hostile than when AI inspections outsized every fleet in the game by a 3-5x factor, but there's still basically no reason not to be at war with them.
Pirate commissions are also fine.
Hege too now (on older patches war was ~inevitable or required exploits to avoid after you built a colony).
You don't need capitals in general, by the way. Fast cruisers with cautious officers will survive more often in most battle types and need little instruction to do so. Ships that are too slow to run away or too small to survive shields going down either need micromanagement or will face attrition.
At this point I'm considering editing the save file to give myself 10 billion credits and all of the [redacted] battleships, because cheating sounds like more fun right now.
Their AI is awful now and the skill that controls them doesn't support having more than ~one, so this isn't really viable anymore.