Looking back at your previous posts, I'm assuming you're applying for a Tier 2 visa for him instead of a spousal visa because you don't currently meet the minimum income requirement (just to clear that up in case anyone else wonders why you are not applying directly for a spousal visa).
In terms of the Tier 2 visa, The first step is to receive the Certificate of Sponsorship from the company. I'm not sure how long it will take to get that, as that is the company's responsibility, but you can't do anything else until you have it.
Once you have it, though, you can move on to the next step of the process: applying for the visa (he will need to apply for his visa himself through UKBA).
It will involve him filling out the online application form (http://www.visa4uk.fco.gov.uk/
), then submitting it and paying for it online (current visa cost is £480, but this will increase to £494 from April 6th).
When he does this, he will be prompted to book a biometrics appointment to have his fingerprints and photo taken at a local USCIS application support center in the US. Most people manage to get a biometrics appointment within a few days of submitting the online application.
After the biometrics appointment, he will need to collect the printed application form and all his supporting documents together and mail them to the UKBA consulate in NYC. They must arrive at the consulate within 14 calendar days of the biometrics appointment (and no later than 30 days after the online application date - whichever is sooner).
From there, he just has to wait for the visa to be processed. There is an option to pay for priority processing on the Worldbridge website on the day he mails the documents to NYC. This costs $150 on top of the visa fee, but if should get him 48-hour processing once the application has been received by the consulate.
Once the visa has been processed, it will be sent back to you, and it just needs checking for errors before you book flights and move to the UK.
So, as a general idea, once he has the Certificate of Sponsorship from the company, it's then your actions that determine how long it will take to get the visa. If you are on top of things and have all the paperwork ready to go, you could be looking at it only taking maybe a couple of weeks from them, but if you take a while to sort out the online application, do the biometrics and send the application in (and don't pay for priority processing), it could take a bit longer.Current processing times
for Tier 2 visas in the US, from the application documents being received in NYC are:
Tier 2 Applications decided in January 2013 (246 applications):
0% in 2 working days
47% in 3 working days
71% in 5 working days
95% in 10 working days
98% in 15 working days
100% in 40 working days.