Emery took over as Arsenal manager this summer and has spent just over £70 million on new signings.
Arsenal have signed the likes of goalkeeper Bernd Leno, Lucas Torreira and Sokratis Papastathopoulos.
But Neville believes Emery needs more time in order to fix the team at Arsenal.
“He has to have four transfer windows to make this team his. It’s not Chelsea here, by the way,” Neville told Sky Sports.
“I don’t think this is short term, the recruitment has been so bad there over this last three or four years.
“It’s going to take basically two or three, four transfer windows to sort this out.
“This is a great coach, Unai Emery, he needs three or four transfer windows.
“I don’t care who the coach would be – you could bring Pep Guardiola in here.
“It took Pep Guardiola three transfer windows at City, the first one in the summer, the January and then the summer after.
“Pep Guardiola, the greatest coach in the world with the biggest budget, it’s going to take him [Emery] more than that.”