help! H-3 Visa confusion

I am Canadian wanting to apply for H-3 Training visa. I am confused as to the process, some sites say I have to be in Canada while waiting for approval, and others say I can be in the US. Does anyone know which it is? Is there restrictions on which Visa I can change status to in the future? Any other information on the H-3 Visa would be appreciated.

Well it's a non-immigrant category, so it depends on your current status. You can't enter the US as a visitor with the intent to change to a different category (or let's put it like this, USCIS likely won't let you), but if you happened to be in the US in some other category the sponsor can apply for AOS on I-129.

Or you can apply at the POE with the approved I-797 and any other supporting documentation needed for H-3.

I-129 is hideously complicated and H-3 is a pretty obscure category so I'd recommend doing it at a POE, it will be quicker.

Read this: http://www.uscis.gov/files/article/C2eng.pdf

You can change status to any other non-immigrant status from H-3, obviously you need to qualify for that category.