Late afternoons and evenings should be avoided on weekends. If you're 'connected' while on the road, check the website. Border wait times are updated hourly:
http://www.cbsa-asfc.gc.ca/bwt-taf/menu-eng.htmlDepending on your destination, there is another bridge 45 minutes East, Prescott in Canada, Ogdensburg on NY side. Never much of a line-up there. That's why, unlike Thousand Islands (aka Lansdowne) it's not even on the border wait-times list of ports.