The market is up 2% YTD, but down 4% from peak. It’s a reasonable time to buy (better than peak, at least).
If you must try to time the market, use time cost averaging to reduce volatility from getting a peak (or trough) price when you enter the market, but know that doing so reduces expected returns. The basic idea is to put 1/n of your money in over the next n weeks.
There are other things like real estate and government contacts, but those are less available to the casual investor, except through stock market funds.
https://www.cnbc.com/2021/03/08/how-the-young-plan-to-spend-...
It's possible something could set off the market today that accelerates the whole process, like the upcoming supplementary leverage ratio change. Or, the bubble could continue inflating until doesn't. But either way the whole thing is incredibly fragile and much more complicated than the "Stimulus is good for the economy" talk politicians are peddling.
John Hussman has a nice article on the option value of cash. https://www.hussmanfunds.com/comment/mc201201/
tldr: Suppose I offer you a security that will pay $100 two days from today. You can buy as much of it as you like today at $50, or you can wait until tomorrow. Tomorrow, I’ll flip a coin. If it’s heads, I’ll sell you the security at $99. If it’s tails, I’ll sell you the security at $25. What should you do?
Clearly, if you buy the security today, you’ll double your money two days from now. That’s a 100% expected return for each dollar you invest, over that 2-day period. If you wait, you’ll earn nothing on the first day, but you’ll then have two possibilities. If heads, you’ll get just 1% on your invested money. If tails, you’ll get a 300% return, quadrupling your money. With a 50/50 chance at each, your expected return for every dollar you invest is 0.51% + 0.5300% = 150.5%. So waiting adds 50.5% to your expected return over that 2-day period.