Source: Elines

One seniority based trade run with open time will occur on the 27th of the month at 1500 HDT. 

Seniority Trip Trades are processed in the following manner: The most senior Flight Attendant’s trade request(s) are evaluated. Once one trade is awarded any remaining requests are bypassed, if no trade can be awarded, the program moves on to the next most senior Flight Attendant. This process is repeated for each Flight Attendant, in seniority order, until the end of the list. This process begins again at the top of the list and continues running until no awards can be made or no trade requests remain.

The step-by-step instructions on the seniority trade process can be found on page 74 of the Trip Trade and Adjustments guide. 

After the Seniority Trip Trade (STT) process has been completed real time trading will resume at 2100 that same day.