The term of the 288-member Maharashtra assembly ends on November 9 and that of the 90-member Haryana assembly on November 2.
Notifications for the two assembly elections will be issued on September 27 and the nomination process will begin on the same day. October 4 is the last date of filing nominations.
While scrutiny of nomination papers will take place on October 5, October 7 is the last date for candidates to withdraw from the electoral battle.
The assembly elections are the first after Prime Minister Narendra Modi led the BJP to power at the Centre for a second term in May.
The government's decision to abrogate Article 370 provisions, which gave special status to Jammu and Kashmir, is among the BJP campaign's key themes for the assembly polls.
BJP leaders sound confident of retaining power in both the states, where opposition parties have been weakened with many key leaders from their camp joining the saffron party in the recent weeks.
In Maharashtra, the alliance between the BJP and the Shiv Sena has not been finalised yet, though talks between the two parties have been going in for some time.
The BJP wants to fight a larger share of the 288 seats in the assembly while the Sena wants it to stick to the earlier agreed formula that both will contest an equal number of constituencies.
Both parties could not agree to a seat-sharing deal even in the 2014 polls, leading to them fighting the elections separately.
The BJP had won 122 seats and the Sena 63 seats.They joined hands after the polls to form government.
Asked why elections to the Jharkhand assembly were not announced on Saturday when the country was discussing simultaneous polls, Arora said the term of the state assembly there ends on January 9.
"If the leader of the House there wants to dissolve the assembly and advance the elections, then it is a separate matter. But why should the commission want to advance it," he said.
While there is a debate on simultaneous polls, "unless there is a very clear consensus amongst the political parties on the issue, this cannot be taken as a given template", the chief election commissioner said
Arora was also asked whether the EC will ban the use of Article 370 in election campaigns as it had banned the use of actions taken by defence forces across the border. He did not spell out a clear reply.
"(Article) 370 is a decision taken by the Parliament of India. The only place where it can be challenged is the honourable Supreme Court of India," he said.
Referring to the use of paper trail machines, he said on the lines of the Lok Sabha polls, the commission has mandated that VVPAT slips count of five randomly selected polling stations in each assembly constituency of
Haryana and Maharashtra will be done for verification of the result obtained from the electronic voting machines (EVMs).
The commission also reiterated that while some EVMs fail to function due to "mechanical, structural or physical defect" including faulty switches, broken button, faulty connection, these never record a "wrong vote".
The polling stations where the count is taken up are selected by a draw of lots after the election and before counting.
The EC will set up 95,473 polling stations for over 8.95 crore voters in Maharashtra. In Haryana, 19,425 polling stations will be set up for nearly 1.83 crore voters.