I did something similar for US. Got there on internship visa (J-1 I believe) for 6 months, and then was offered an FTE on H-1B. Back then in 2006 the yearly H-1B were "released" in late May or early June I believe, and they finished in a month or so, so this might be good to take into consideration when planning. I believe a good time for the employer to file application is in April or May, and then the H-1B is typically ready in September.
After the internship some other option came up for me back home in Sweden so I never used my H-1B.
Note: This was not for a startup, but for an established company with HR and all that stuff. But the timing aspects should still apply I believe. As a side-note I eventually moved to Singapore, and getting an "employment pass" (equivalent to US H-1B) here was extremely smooth, comparing to all the work to get the H-1B for US.
I was accepted for a startup in Philadelphia from Europe; but the salary was quite low. So a sponsor may push the salary quite low; for them you would have an advantage in this case.
I finally settled agreeing to work for 3 months unpaid internship, at the end of which I got my first job in Australia.
It ain't easy to wing it, so be ready to think outside the box.