The Red Devils are yet to flex their financial muscles while their rivals are already strengthening their respective sides.
Manchester United have a new man in charge with the appointment of former Ajax Amsterdam boss Erik Ten Hag as new manager.
The Dutchman has a major rebuilding job on his hands especially with Manchester United having already lost the likes of Paul Pogba, Nemanja Matic, Juan Mata, Jesse Lingard and Edinson Cavani already this summer.
Barcelona midfielder Frenkie De Jong, Christian Eriksen, Antony and Christopher Nkunku have all been linked with moves to Old Trafford but United are yet to get going with their transfer business.
United finished sixth and a massive 35 points behind champions Manchester City last season while 34 points separated them from second placed Liverpool.
The Premier League's top two have already strengthened with big money signings already as Manchester City have brought in Erling Haaland from Borussia Dortmund while Liverpool have captured Darwin Nunez from Benfica.
Neville has urged his former employers to take a cue from their rivals and get their business done early.
"The others seem set and ready, yet United can't get moving," Neville wrote on Twitter on Thursday.
"[Ten Hag] needs his group together [as soon as possible] to mould them. Bringing them in late will only make it harder for him. [Fingers crossed] it happens soon!"
Manchester United will host Brighton and Hove Albion in their opening game of the 2022/2023 season.
