I've been actively trading the market for about 25 years now and have watched thousands of professionals try to time the market. Many use complex macro arguments, some use fancy technical analysis, and some use valuation and a variety of computations.
Sometimes they get it right but most of the time they get it wrong and when they do get it right the timing usually is not so great.
My experience is that the only way to time the market with any degree of certainty is to simply look at what is happening to your brokerage account. The secret to effective market timing can be summed up in seven words: "When stocks are going down, sell them."
That is all you need to know. When you are losing money and the stocks you are holding are dropping in price, then sell them. You can always buy them back or find new stocks to buy but the most important rule is to protect capital and you protect capital by not holding stocks that are declining.
Yes, this may sound simplistic and a bit sarcastic but it works. Institutional Wall Street and the very serious pundits don't like advice like this because it undermines what they are selling. They want you to believe that the market is much more complicated than that and that serious people with serious money need them in order to survive and prosper. You don't need them to tell you when the market is acting poorly. You can figure that out pretty quickly by looking at your profits and losses.
Currently, most of the stocks that I'm trading are acting rather well so I'm not selling them. If you own different stocks you may feel differently but the only timing device you need is the stocks in our portfolio