It is recommended that you begin the visa applicaiton process as soon as you begin considering travel to the US. Details on US visas for foreign business travelers is available at http://www.travel.state.gov/content/visas/en/business.html.
The visa application often includes an interview in which you will be expected to demonstrate that you are traveling to the US for business purposes. The following documentation may be required/recommended: official letter of invitation, registration confirmation, itinerary, proof of residency, evidence of employment.
WJTA can provide an official invitation letter to registered attendees and current members in order to assist in the visa process. Email email@example.com with your contact information and passport information and we will provide an electronic letter of invitation.