>The risk you take is will it jump up on the one day you are selling

Actually I think the risk would be that it goes up during the next 30 days after you sell. You cant sell a stock, claim a loss, and then buy back the same stock within 30 days.

Superficial loss

A superficial loss can occur when you dispose of capital property for a loss and:

• you, or a person affiliated with you, buys, or has a right to buy, the same or identical property (called "substituted property") during the period starting 30 calendar days before the sale and ending 30 calendar days after the sale

http://www.cra-arc.gc.ca/E/pub/tg/t4037/t4037-e.html#P3498_137482