And it'll be at least another week before the one-time feared pass-rusher will have a chance to make his debut.
A day after acquiring Merriman off of waivers, Gailey announced after practice Thursday that the player is tentatively scheduled to report to the team on Friday. Gailey also ruled the player from playing in Buffalo's game against Chicago (4-3) at Toronto on Sunday.
Under NFL rules, players claimed on waivers have five days to report to their new teams.
Looking forward, Gailey said that should Merriman pass all his necessary physicals and depending how fresh he looks in practice next week, there's a chance the player could play against Detroit on Nov. 14.
"Mentally, it won't be that hard, because he's used to the 3-4 defense and what we're doing," Gailey said. "So it depends on what kind of shape he's in. And that will determine how much if any he plays."
San Diego's 2005 first-round draft pick, Merriman was waived by the Chargers on Tuesday, three weeks after he was placed on injured reserve because of a calf injury. The injury was designated as minor, meaning Merriman was to be released once he was deemed healthy by the Chargers.
The Bills (0-7) added Merriman in a bid to improve a defense that's struggled against the run and has had difficulty generating a pass rush.
"Any time you can pick up a quality player, it doesn't matter what position it is, you've helped your football team," said Gailey, in his first opportunity to discuss the move. "We're just fortunate that this guy has a lot of tools. It's not just a few things, he's got a lot of tools."
On the injury front, starting inside linebacker Andra Davis missed practice for a second straight day due to a nagging shoulder injury, and his status is uncertain for this weekend.
The Bills have already laid out the welcome mat for Merriman by assigning him a locker, complete with a nameplate and the number 55. The locker has already been filled with an assortment of Bills T-shirts, a team cap, a practice jersey and helmet.
Merriman's locker is directly next to linebacker Paul Posluszny, who is eager for his new teammate's arrival.
"I think we're all excited. He's a big-time player, Pro Bowl player, who has really played well defensively in the past," Posluszny said. "The more big-time players we can bring, the better."
Buffalo's defense ranks last in the NFL against the run in allowing nearly 189 yards a game. And their pass-rush has struggled as the team has not found a replacement for Aaron Schobel, who was released in August after he failed to report to the Bills while contemplating retirement.
Defensive end Marcus Stroud was encouraged by Merriman's addition, noting it's a sign that the Bills front office is doing what it can to help a team off to its worst start in 26 seasons.
"Anything can be a jolt right now," Stroud said. "We're in a bad situation right now, but everybody here is doing the right thing to try to turn this ship around."
Nicknamed "Lights Out," for his hard-hitting style, Merriman is a three-time Pro Bowl selection. In 60 career games, he has 43½ sacks -- but only four in his past three seasons. The dropoff is a result of a series of nagging injuries that have hampered his effectiveness.
Merriman missed most of the 2008 season after undergoing reconstructive knee surgery, and had only four sacks last year while attempting to find his hard-hitting form.
After sitting out most offseason workouts and part of training camp to protest his contract status, he was slowed by an Achilles' tendon injury and then a calf injury.
He's also encountered on- and off-field problems.
Merriman was also suspended four games in 2006 after testing positive for steroids. He blamed the positive test on a tainted supplement, which he never identified.
He also brought unwanted attention off the field. He was arrested just before the 2009 season after reality television star Tila Tequila accused him of battery and false imprisonment at his suburban San Diego home. No charges were filed, and Merriman and Tequila settled dueling lawsuits.