How much are you investing?
Personally, I don't even think it's worth diversifying past a single low-cost stock index fund (such as VTSAX) until you have at least $50k invested.
There are just too many pitfalls. You need first get really comfortable and understand asset allocation. Be aware that a lot of the "conventional wisdom" is too heavy on bonds for a FIRE scenario. Heavy on bonds is fine for a 10, 15, maybe 20 year retirement timeframe. Longer timeframes need more of the growth from stocks.
Once you are comfortable (REALLY comfortable) with an asset allocation, don't put less than $10k in any one fund. Decide on when you will rebalance (January 1 and July 1? January 15 and July 15?) - and STICK TO THE PLAN. Way too many individual investors screw themselves over trying to time the market.
I have considerably more than $50k invested, and it's almost all stocks - mostly in VTSAX. One $5k* I-bond that doubles as our emergency fund. One individual stock left from a long time ago, which I plan to sell the rest of in the next year. It's around 10% of invested assets.
Should I just sell the individual stock now? Yes.
Am I having emotional hurdles to do so? Yes.
So, I know wherefrom I speak with the temptations of market timing ;)
*Well, plus appreciation. It's somewhere over $6k now.