Sherrill, who signed a one-year deal as a free agent after pitching for Atlanta last year, likely won't crank it up until full-squad workouts begin this weekend.
"We're going to get him out here in the next 3-4 days," manager Eric Wedge said. "I'm just really aware of the workload he's had and the fact he's a left-hander. With those guys, as a manager you can get them up every night if you want to. So there has to be a certain discipline with how you use those guys, especially with George being a veteran and a guy you know you're going to go to. He knows himself well, so there's no reason to rush that."
Pitching coach Carl Willis noted that Sherrill "fatigued a bit toward the end" of last season and has plenty of time to work himself into shape this spring, with the Mariners being the first Major League team to report by a full week due to their early season opener in Tokyo.
"We're here a long time, so there's no reason to get him started right away," said Willis. "We'll get him going here in the next few days."
Willis said the first four days of camp, which have now seen all the other pitchers throw two bullpen sessions apiece, have gone well.
"It's always an important step, that second bullpen when guys come in," he said. "As much as you tell them not to get too giddy that first time out, they want to show you what they can do and they're excited. But everyone now has gone through two sides and physically they seem to be where they need to be, so we'll keep moving forward."