Will I lose my Job if I don't switch streams on time?

I got ranked 1 for an 8-month co-op and plan on accepting it. However, I haven't changed my co-op stream yet because I wasn't sure if I'd get the job.

I plan on switching streams ASAP but WW will be matching employers tomorrow. If my co-op sequence on WW says I'm up for a 4-month co-op will WW automatically eliminate me and match with the person who was ranked 2nd?

This doesn't really seem like I possibility but at the same time I really don't want to go through looking for a job again so if anybody knows the answer to this please help!!