Brandon Wason and Mark Goodacre offer timelines for Paul's activity. In the past I’ve sided more with Brandon’s view of the dating of Galatians (earlier), though I’m less confident these days. It’s always been the most difficult letter to date.
For a more radical chronology, see that of John Hurd, used on Bob MacDonald’s website. Hurd is known for keeping the testimony of Acts at arm’s length and relying solely on the letters. He puts Galatians late (around the same time as Romans), and II Thessalonians as the first letter, written in 41, about five years before I Thessalonians.