First of all, we are not talking about your regular scheduled contributions to your 401(k), 402(b), 457(b) or IRAs.  For those contributions either by every paycheck period or on your own schedule, you allocate the money to buy funds.  You should continue to contribute to your retirement accounts without fail.  You should never time the market with your retirement savings!

http://blog.wenxuecity.com/myblog/72332/201801/19668.html?

This is not what we are talking about here!  We are talking about the extra cash from selling a property, receiving a cash gift from your parents, and for whatever the reasons, etc.  When and how do you put the cash into the market?

You need to wait for an entry point to get into the market.  The entry point would be either a recession or a correction.  A recession is by definition two consecutive quarters of negative GDP and a correction is the broad equity market down 10% from its recent high.  When we say the broad equity market, we usually refer to S&P 500 Index. 

While you are waiting for an entry point, I would suggest you to leave your cash in short term CD for now, or you can buy short term US treasury, build a treasury ladder by using 4, 8, 13 and 17-week treasury bills, check the following link.

https://www.treasurydirect.gov/.

When the entry point level has reached, you should put the money into the market with a dollar cost average method which will help spread your risk around. 

http://blog.wenxuecity.com/myblog/72332/201810/34880.html. 

On March 28th, 2024, S&P 500 Index has reached the historical high of 5,264, 10% correction will be around 4,738 level.  If we reach that correction level,  I would sugguest to use dollar cost average method to get into the stock market.  

On March 21st, 2024, Nasdaq Index has reached the historical high of 16,538, 10% correction will be around 14,884 level.  

I have listed the following several major entry points in the past 14 years for your reference.  As a matter of fact, there were a couple of 10% down entry points in between as well.