The striker has not played a senior game in 14 months.
The 23-year-old hitman has endured an injury-ravaged last 14 months following a knee injury, but the former Peterborough United man could make an appearance in tomorrow's visit of Blackburn Rovers for what will be his first squad inclusion since the layoff.
Assombalonga, who netted 15 Championship goals in 27 appearances last term, has emerged as one of Forest's best players since joining in 2014, but Reid says that supporters will do well to give him time to get back up to speed following such a lengthy absence.
The 33-year-old said to the club's official website: “He’ll be in the squad. Whether he plays, or how long he plays, I suppose will be determined by how the game goes and what the manager’s feeling at the time.
“We have to be patient with him – this is the start of his first-team return and there’s still a lot of hard work for him to do before he gets back to the Britt Assombalonga he was before he got injured.
“He knows that, we know that and I think it’s important the fans understand that as well. He’s a very popular character so I’m sure the fans will get behind him and give him all the help he needs.”
It was a broken kneecap which kept Assombalonga out for so long, and such a long-term absence is bound to leave the striker somewhat rusty.
With Forest more or less safe from relegation, the objective will be to keep Assombalonga fit for the remainder of this campaign and have him fit and firing for the start of the 2016-17 campaign.