u/Beginning-Island-560

First time poster and looking for advice.

I have a chuck of money saved up and was thinking of putting into an index, something like the S&P 500. Low risk and friendly for beginner.

Obviously it has AAR around 10% but I was wondering if there is any good certain time periods to put that money into it because I've seen the S&P rally hard the past month. Is it better just to buy now or wait a little?

Any advice greatly appreciated