Prime Minister Gen Prayut Chan-O-Cha's announcement came after voters approved the draft charter in Sunday's referendum vote.
Prayut did not comment on the referendum result but said the poll process would happen in 2017 as planned.
"Please have confidence in the roadmap. I've never said otherwise," the prime minister said.
Speaking to reporters, he dismissed a suggestion that the polls could be postponed to 2018.
"Let's count today as Day 1 on the roadmap schedule. If you follow the roadmap it would put us at November 2017 when the whole process is complete. So why would the elections be held in 2018?" he said.
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But critics have argued that the new charter will perpetuate army control with the armed forces and an appointed senate retaining decisive influence over future elected governments.
Under the new charter which would be Thailand's 20th since the military abolished an absolute monarchy in 1932, a junta-appointed Senate with seats reserved for military commanders would check the powers of elected lawmakers.
The military took power in May 2014 with Prayut as premier after years of street protests and clashes between two rival factions identified by the colour of their shirts - red and yellow.
The military's strategy is to reduce the influence of Yingluck's party by increasing the power of other parties and the military.
The constitution would also increase the number of seats in the 500-member lower house chosen by proportional representation, decrease the number chosen by district elections and limit the number of proportional seats that can be awarded to a single party.