When planning your travels to the United States it is important to simply make sure that you do not have any type of criminal conviction on your record. One of the best ways to do this is to obtain your criminal record from the Canadian police department. You can provide the department with your fingerprints and they will be able to pull up your criminal record for you. This is the easiest way to determine whether or not anything will show up should a border patrol agent run a background check on you when you are attempting to cross the border.
When applying for a waiver, it can take anywhere from six months to 18 months for it to be approved. For this reason, it is important to make sure that you plan ahead for your trip into or through the United States to make sure that you have your waiver in place before you get to the border. This can be essential to your travels.
If you take the time to make sure that you have a waiver in place, it will make travelling across the border much easier. Typically, a waiver will be good for 1, 3, or 5 years. The time frame will depend directly on your waiver application and how serious the crime was that you committed. You will want to make sure that you apply to renew your waiver well before it expires so that your entry into the United States is not disrupted at any point.
Having a valid US student visa or USA work visa does not overcome criminal inadmissibility when attempting to cross the border. Flying into USA with a criminal record is also a problem even if your final destination is not in the country (in other words, non-Americans with a criminal past can't even layover in the United States). The absolute only way to visit the USA with a record of crimes is to apply for a US Waiver for Entry.