I hope that you're not planning to travel anywhere else abroad this year. A US visa application can effectively prevent you from travelling overseas for many months.
The first part of the procedure involves getting a copy of your criminal record from your local police force. (This can take up to 6 weeks because the police have 40 days in which to provide the information). Then you have to make an appointment for an interview in London. (The waiting list is usually around 2 weeks but, at peak times, it can be much longer). After your interview, the
minimum time (according to the US embassy website) before you'll hear whether your application has been granted is
'14 to 16 weeks'. During this period, your passport will be held at the US embassy, so
there will be a period of around 4 months when you won't be able to leave the country. Also, you shouldn't book your holiday in the USA until you've heard the result of your visa application. It's possible that you might suffer a great deal of inconvenience only to be disappointed at the end of the procedure.
It is frequently pointed out, here on AB, that US immigration officials don't have direct access to UK criminal records. Only a few days ago, someone posted to say that they've been admitted (by lying on the visa waiver form) with Class 'B' drug convictions. However, the UK authorities do pass some information on and it's possible that Class 'A' convictions might be included in this information.
The full procedure for a visa application is outlined in my posts here:
http://www.theanswerbank.co.uk/Travel/Question 289769.html
Chris