To set date since when a transaction item should be processed, use Postpone property of Add Queue Item activity. This property can be filled in with relative dates such as DateTime.Now.AddHours(2), DateTime.Now.AddDays(10) and DateTime.Now.Add(New System.TimeSpan(5, 0, 0, 0)). Additionally, you can use the US notation to add an exact time, such as 12/10/2017 07:40:00. Automatically correcting this date is available. For example, if you write 8 9 2018 9:0, it is automatically transformed to 08/09/2018 09:00:00.
In the United States, dates are traditionally written in the "month-day-year" order, so 7 1 21 8:0 will result in the item being postponed till 1st of July 2021, when 1 7 21 8:0 will postpone it to 7th of January 2021.
Using DateTime.ParseExact("1 July 2021 08:00","dd mmmm yyyy hh:mm", System.Globalization.CultureInfo.InvariantCulture) will result in an error, as notation for month is capital MM, while mm represents minutes.