How to Change Permalinks without Losing Traffic

Hi,

I am Vijay. Recently I have transferred my website from Blogger to WordPress. So In Blogger my Permalinks was like https://www.mywebsite.com/year/month/postname.html

Now in WordPress I want to change this to https://www.mywebsite.com/postname

I know How to change permalinks in setting option. But If I directly do this, then I will lose my traffic which I am getting from Search Engine. So I want to redirect my old permalinks to new one without losing traffic.

Please Help asap. Thanks in Advance