Back in 2005, eCommerceBytes conducted a survey to determine the best day of the week and time of the day for sellers to end auctions on eBay. In a recent survey (nearly 9 years later), the results shows very little change.
62% of sellers (compared to 56.8% in 2005) note that Sundays have the highest bidding activity on eBay, deeming it the best day of the week to end an online auction. Over half (53%) of these respondents also agreed that the best time of the day to end an auction is between 6pm and 9pm Pacific time.
Take a look at the original article from eCommerceBytes to learn more about these results and what other strategies sellers are using: http://www.ecommercebytes.com/cab/abu/y214/m06/abu0361/s02