The manager gave the updates ahead of the Eagles' first competitive fixture in three weeks, following a mid-season training camp in Marbella and a two-week international window.
On Michael Olise – absent from the side since early February – Glasner said: “It’s good news, but he’s not in the squad [for Nottingham Forest].
“He did many parts of training this week – not all the parts – and he’s on the way back, but the Nottingham game is too early, the Bournemouth game [on Tuesday] is too early, then we will see in the next days.
“Of course, Michael showed in the sessions that he’s a brilliant player, but the focus is on all the other players tomorrow because I don’t look too far in the future. It’s important [to focus on] the Nottingham game, and Michael won't play, so the focus and concentration is on all the other players.
“Jeffrey Schlupp is back after his injury. It's the first game after many weeks and the group is getting bigger and bigger and that gives us more options, and it's very important for us that the players come back from injuries.
"The fit players tomorrow are more important for tomorrow for winning the game at Nottingham.”
Glasner also provided updates on Palace’s returning internationals: “The only injury we had and are suffering is Sam Johnstone with the English national team. He had surgery on his elbow and he will be out until the end of the season.
“It’s very tough for him and also tough for us, but with Dean Henderson, we have a great goalkeeper. He’s now the No. 1 and we fully trust him.
“Daniel [Muñoz] is alright – just a small issue [when with Colombia], but nothing serious, so he will be with us tomorrow.”
On the news that Johnstone would miss the rest of the season, particularly in the build-up to Euro 2024, Glasner admitted: “He’s of course disappointed, but he’s now starting the rehab process, and he has all our support that he will be back as fast as possible.
“This injury takes several months. Yes it’s tough, but he’s a great sportsman and he has all our support.
“I saw the video [of his injury] and very often it doesn’t look really bad, but the outcome was bad. It was a shot and I don’t know how often you have it in a career as a goalkeeper, 1000 times? And once, it has a bad consequence, and this was the time – but nobody’s to blame.
“We will support him to come back stronger than before. He’s been a professional for many years and I think it’s not his first injury, so he will have to deal with it as a professional player. He will deal with it, and he has our support, but it’s too far in the future to talk about it.
"Now he's had the surgery, and now it's recovery time, and then the rehab process will start."
On long-term absentees Marc Guéhi and Cheick Doucouré, Glasner was hopeful both could return to the action before the end of the season.
The manager said of Guéhi: “He’s working very hard. I see him every day here, and also our medical team is working very hard with him. I don’t know how long it will take but I think, I believe and I trust he will have several minutes this season.
“The same [with Doucouré]. I’m not a doctor so I don’t know exactly, but all the players are working really hard with our team. They have all the support, so there may be some minutes, but maybe Cheick is the one who will come back latest from all the injuries.”