The source used will be the UF Election Lab. If the don't publish data, other reputable sources will be used.

I expect an initial estimate within a few days of the election; if it's close to boundary I will wait a few weeks to resolve the relevant threshold in case of any revisions. The market will remain open until resolution.

Turnout figures from the last few midterms for reference:
2022: 46.1%

2018: 50.1%

2014: 36.7%

2010: 41.0%

2006: 40.4%