Hi:
Good question… look it up and report here.
https://www.google.com/search?q=diablo+iii+fastest+start+to+season
Show me that you care enough about the topic to at least search for it… and learn about it… before asking for help.
This may come in handy too: Reminder - Do NOT do the Challenge Rift from 11th April until after Season 26 has started