The best time to go to is 2008 because that year and few next one good things happened and it was not that long ago so the technology would not be much different.
When time travelling I would make my self 21 years old so I could skip school, university and be old enough to get a job or shop online. In 2008 the oil price was very high and people made lots of money working there. If I could save lots of money if I worked there when the oil price was so high. That would allow me to invest in things cheaper back in 2008 and sell them for high in 2020.
There are things I could buy when they used to be cheaper back then are bitcoin. Back in 2009 bitcoin cost less than 1 cent and the highest price ever for one was over $25000 in December 2017. By investing 1 dollar I could make over 2 million dollars today. I could also buy rare cars cheaper, the 2006 Ford GT is a sports car that is powered by a supercharged 5.4-litre engine that has a top speed of 300 mph. Only 4000 cars were made and the price for one today is over $666000 but from 2004 to 2008 the price was only $200000. 2007 Porsche Carrera GT is another car that is double the price today then it was in 2008.
With today’s knowledge, I could predict the future and prevent many catastrophes like a 7.0 magnitude earthquake in Haiti that killed 230,000 people in 2010. August 10 of 2008, Toronto Explosions leaves 2 dead and thousands evacuate their homes. In 2011, 16000 people died in the 2011 Tōhoku earthquake and tsunami. There are many more small things that would not have deadly results if people know about them before they happened.
If people knew the future, they could make many good financial decisions, and prevent deaths.