First and foremost, make sure that you fulfil the requirements to qualify for a convertible ARM. You will be required to prove your citizenship or legal resident status as well as show your income. Other requirements will vary from lender to lender so do get information in advance so that there are no issues at the time of the procedure being finalised.
While you are buying the house, do not opt for a zero down payment option even if you qualify. Put down at least five percent down payment to qualify. The minimum down payment to qualify may be more in some areas.
The convertible ARM may be a subject to the credit score you have. The higher the beacon score, the better it is for your chances to qualify. It is also useful if you have a clean credit history with no charge offs and the length of the history is several years long. The eventual decision is not taken purely on the beacon score but also the length of the history and your payment habits.
The loan is for properties up to $650,000 and will not cater to properties valued higher than that. Also, it may cater to certain properties and not to others. Be sure that your property type is covered by the rules of qualification.
Just do not stick with one lender and chance your arm with several financial service providers. This will help you in getting the best rate that you will be paying for a few years to come. Once you shop around and know what the market has to offer, make an informed choice.