When to file to be taxed as S Corp?

[Shawn Choplin]

Just created an LLC to do fix and flips through and was strongly considering being taxed as an S Corp to avoid, not evade:), paying the 14 or 15% self employment tax on the dividends above what I'll pay myself as a reasonable salary. I tried looking at other forums for my answer but couldn't find it.

When exactly do I need to declare that I'm wanting to be taxed as an S Corp?  Now or next tax season?