Did some more digging on the CBA.
Short version: Reilly would have to have 10 professional games this season for it to account as an accrued season, which would put him one year closer to arbitration rights and future UFA status.
This is a bit different than an ELC signed by a younger player. The younger guy (with slide risk) would have to play 10 NHL games, an older guy would have to play 10 professional games at any level.
Here are the important dates and who plays that day:
March 22 - Springfield (home)
March 24 - Columbus (home)
March 27 - Springfield (home) and Columbus (at CHI)
March 28 - Springfield (home) and Columbus (at STL)
March 29 - Springfield (at Worcester)
March 31 - Columbus (home)
April 1- Springfield (at Bridgeport)
April 2- Columbus (home)
April 3 - Springfield (home)
April 4 - Springfield (home) and Columbus (home)
April 6 - Columbus (at TOR)
April 8 - Columbus (home)
April 10 - Springfield (at Hartford) and Columbus (home)
April 11 - Springfield (at Syracuse) and Columbus (at NYI)
April 17 - Springfield (at St John's)
April 18 - Springfield (at St John's)
This provides the possibility of 16 pro games, although it wouldn't happen...the idea of having Reilly play pro games on five consecutive days while flying back and forth is so absurd it doesn't warrant further discussion.
However, here are the important days as it relates to Reilly's current status as a college player:
B1G tournament: March 19-21. Minnesota is going to be a top-4 seed in the tournament. The top two seeds get a bye to the second day (March 20). If Minnesota is a #3 or #4 seed and loses in the first round, they may miss the NCAA tournament entirely, making Reilly available in time for the March 22 game in Springfield if he signs. If Minnesota wins it or finishes #2, they'll go to the tournament. #3 is a possibility.
NCAA tournament first round: March 28 and 29. If Minnesota loses in this round and Reilly signs, he could still hit the 10-game threshold.
NCAA tournament second round: March 29-30. If Minnesota loses in this round and Reilly signs, he could still hit 10 games, but it would get a bit more dicey.
NCAA Frozen Four: April 10 and 12. If Minnesota makes it this far, there's no way for Reilly to hit 10 games.
EDIT: Missed the CBJ March 24 game against Anaheim, and added in physical location of each game.
The only way for Reilly to get 10 NHL games would be if Minnesota misses the NCAA tournament entirely. The tournament selections are made on March 22. Thankfully the 10-game threshold applies to all pro games, not just the NHL. Those two games on April 17 and 18 against St. John's are immensely helpful, as will the AHL playoffs unless Springfield completely collapses.