Not that it matters much anymore as there are only 2 more monthly releases. The easiest way to decipher or to get an accurate gauge is looking at last years press release + timing of any current conferences.
* LY press release was on Tue, 5/7/13
* Conference presentation at Jefferies on Wed, 5/7/14
Typically, monthly numbers have been a pre-market release. If it follows LY trend, the monthly numbers would come out pre-market on Tue, 5/6. (I guess there could be an outside chance they could delay the numbers until Wed to coincide with the conference.)