The Scottish Government plans to create a Scottish Police Authority first, with the new chief expected to be in place towards the end of the year.
The Association of Scottish Police Superintendents (Asps) has already called for the chief constable to be appointed earlier.
Brian Docherty, chairman of the Scottish Police Federation, said: “How the service is structured and delivered are questions for the new chief constable to decide. What the command structure will look like, how and where departments will work, and who will work where are all decisions for the new chief constable.
“Unless he or she is appointed very soon, the April 2013 start date will be upon us without these important questions being answered.”
A Scottish Government spokeswoman said: “Appointing a chief constable soon needs to be balanced with ensuring the process is as open and transparent as possible, and getting the right person for this very important post so that everyone can have confidence in the leadership of the new service.
“We expect this to happen by the end of the year at the latest.”