when do futures open on sunday?

On a general note, futures trading from anywhere in the world starts by 6 PM Eastern Standard Time. But let me do the time conversion for NY, London and Sydney:

If you are in New York, Futures trading starts on Sunday at 6 PM New York Time

If you are in London, Futures trading starts on Sunday by 11 PM London time (GMT)

If you are in Sydney Australia, Futures trading starts on Monday morning by 9 AM Australian time (AEST)

Here in London, futures trading starts around 11 pm in the night but the spreads are always wide on Sundays. If you have a good futures trading strategy, you can still trade on Sunday nights as Sundays tend to set the direction for the week.

6 PM EST is when the futures market opens for trading every Sunday (except when the stock exchange is on market holiday or something). On Sundays you may not get good liquidity on some futures so the best futures I trade on Sundays for good liquidity are S&P 500 futures mini, crude oil futures, and gold futures.