The 2015 H1-B quota is already exhausted, so you can only apply first week of April 2016. Assuming your engineer wins the lottery* they'll be able to work starting October 2016.
* There are 65,000 visas. In 2015 there were 233,000 applications so probability of winning = ~28%. It will probably be worse in 2016.
* There are 65,000 visas. In 2015 there were 233,000 applications so probability of winning = ~28%. It will probably be worse in 2016.
http://www.uscis.gov/news/alerts/uscis-completes-h-1b-cap-ra...