You can do it right away - and in fact, basically have to, since the other part of the puzzle is that you MUST be insured. Ultimately it's not really that clever - the state just acts as a giant group purchaser, and the fact that it's compulsory spreads the risk around so that it's not an adverse selection problem. It seems silly to shill for it, but all the details are (more or less) explained on the site: http://www.mahealthconnector.org
Note that the reason you can apply for it right away, unlike other state "benefits", is that it's not really a benefit - there's no subsidy (at least, not for self- or startup-employed folks like me who very well can afford it), so there's no real cost to the state of letting 1, 2, or 17000 more people buy in (and in fact there's an advantage, because you increase the risk pool).
Note that the reason you can apply for it right away, unlike other state "benefits", is that it's not really a benefit - there's no subsidy (at least, not for self- or startup-employed folks like me who very well can afford it), so there's no real cost to the state of letting 1, 2, or 17000 more people buy in (and in fact there's an advantage, because you increase the risk pool).