When do you wish to study math? It may be a bit late to start Fall 2013, especially if you want funding.
If you wish to begin Fall 2014, you might consider the following. The Math GRE is offered in April, October, and November. The first applications are usually due in December (2013) and many in January (2014). So you may wish to schedule Math GRE tests in October AND November. This will give you much time to study, but you will have your scores before December application due dates. You can choose to submit the higher of the two scores, so if one goes poorly, you still have a chance.
It is definitely possible to do graduate school in the USA or Europe in math with a background in electrical engineering. However, it is crucial that you score well on the GRE Mathematics Advanced Subject Test. This will largely determine which schools are possible. Without a B.A. in math you must prove through the test that you can do well in mathematics. Continue studying hard.
About where to study...this might be a good place to start:http://grad-schools.usnews.rankingsandr ... s-rankings
Rankings are never perfect. It also depends on the subfield of mathematics. However, it will give you an approximate idea of the perceived quality of schools.
Next you could look at this thread:viewtopic.php?f=1&t=1003
It will give you some data points for admission/rejection to some of these schools. After finding your test score, you can narrow down the range of schools. It is wise to apply to schools of varying quality. Some high up the list and some lower on the list, where you feel certain you will be admitted.
Each university's department webpage offers a more detailed list of application requirements. Yet, the basic requirements are a transcript of grades, GRE General Test, GRE Math Test, and a statement of purpose/goals. Some ask questions specific to the individual university. I would look more carefully at application details around July/August. For now study hard, and if possible take some proof-based math classes.