How to decide how much to invest when in your 20s?

I often see the recommendation to keep 3-6 months of costs of living in your savings. Now I guess it’s different when you’re in your 20s and still living with your parents. I have quite a lot saved already and it’s just been sitting in my bank account which looking at how much it would have gone up if I started investing in etf’s years ago really feels like a waste. So I’m wondering, what would you suggest in my situation (someone living with parents, low cost of living and trying to minimize spending overall. Hoping to find a place to live (renting) in the next 2 years and having 20k+ in savings). Put a significant amount in stocks now or wait till I’m settled with my own place to live?