Ch Supt Alan Spiers said call handling would move from its control room in Dundee to its national service centre in central Scotland in that month.
The processes to close control rooms in Aberdeen and Inverness would take place from August to October, he said.
Highland Council has raised concerns about the loss of local knowledge once the Inverness service shuts.
Council leader Margaret Davidson said the local authority "was convinced that it was safer" that calls from within Highland, a region about the same size of Belgium, were handled locally.
Ch Supt Spiers told BBC Scotland's Good Morning Scotland programme that Police Scotland acknowledged that were concerns about the restructuring.
But he said the current set-up of call handling was not "practical or sustainable" for a national force, and its change programme would be carried out with due regard to proper "governance, measures and independent assurances".
Control rooms in Inverness and Aberdeen were originally scheduled for closure in 2015.
However, that original closure plan was halted after an HM Inspector of Constabulary (HMIC) investigation began into a crash on the M9 in July which was not followed up by police for three days.
John Yuill and Lamara Bell died after the crash near Stirling.
In November, weaknesses in Police Scotland's roll-out of its new national call-handling system were highlighted in an HMIC report.
Derek Penman said the oversight of the project was inadequate and made 30 recommendations.
Ch Supt Spiers said the force was working through through those recommendations and would have this work completed by June.
He said: "They are at different stages of completion. We also said we would go much further than what the recommendations have said.
"We have also stated the remaining phases of our reform programme would only proceed when the police authority and HMIC were completely assured that staff, systems and procedures and processes were in place."

The 27-year-old forward was a free agent, having recently left Hull City when his contract expired.
He spent four years with the Tigers, making 118 appearances for them and scoring 15 goals.
Aluko, who can play on the wing or through the middle, represented England at youth level and has since won seven caps for Nigeria.
He began his career at Birmingham City and played in Scotland for Aberdeen and then Rangers before joining Hull.
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Henrikh Mkhitaryan's sublime solo goal proved the difference as second-placed Dortmund moved within five points.
The Armenia captain ran at the away defence from deep before firing into the bottom corner from 20 yards.
Pep Guardiola's side can restore their eight-point lead with a win at relegation battlers Augsburg on Sunday.
Bayer Leverkusen moved into third when they fought back from behind to win 2-1 at Darmstadt, while Hertha Berlin dropped to fourth after losing 2-0 at Stuttgart.
Second-bottom Hoffenheim, with new 28-year-old manager Julian Nagelsmann taking charge for the first time, drew 1-1 at relegation rivals Werder Bremen.
Police Scotland will be ready to begin a process of changing its system for handling calls from June this year.
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Fulham have signed Sone Aluko on a two-year contract with the option of a further year.
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Borussia Dortmund narrowed the gap on Bundesliga leaders Bayern Munich with a hard-fought win against bottom side Hannover.