The firm said in February that it was cutting up to 1,080 posts over two years, about a fifth of its Northern Ireland workforce.
While the overall total has not changed, up to 630 will go this year, as opposed to the 580 stated initially.
A Bombardier spokeswoman said: “ We have advised our employees that, having reviewed our requirements, regrettably, we need to pull forward some of the workforce reductions we had expected to take place next year.
“In February this year, as part of a global downsizing across Bombardier, we announced a workforce reduction of up to 1,080, comprising 580 in 2016 and 500 in 2017.
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“This overall figure of 1,080 has not changed. However, we now expect more people to leave this year - potentially up to 630 - with the remainder leaving in 2017.”
The Canada-based multinational has been under financial pressure and invested large sums on its new C Series jet which is crucial to many jobs in Belfast.
The spokeswoman said: “We appreciate that this is a very difficult time for our workforce and their families, and we are doing all we can to mitigate the numbers of compulsory redundancies.
“However, it is crucial that we continue to evaluate all opportunities to significantly reduce our costs and improve our competitiveness, in order to help secure our long-term future.”
Ulster Unionist representative for East Belfast Andy Allen said one of the reasons for the change of plan was that the company will give core employees in some areas the option to take redundancy if they do not want to downgrade to a lower position.
“Whilst I am relieved that Bombardier has reaffirmed its commitment to the C Series programme and to Northern Ireland’s critical role in its delivery, these earlier than planned job losses show the situation is still deeply unstable.
“This underlines the necessity for the incoming Executive to devise quickly, and with the essential input of business and unions, a manufacturing strategy for Northern Ireland.”