Don't worry about getting a Bridging Open Work Permit (BOWP). Just apply for it, which is enough to maintain your status as an implied status.
I submitted my BOWP application one week before my PGWP expired, but I received my ECOPR after it had already expired.
That is true, but the maintained status only allows you to continue working under the same conditions as your old expired permit. If you're on a work permit tied to a specific job then you won't be able to start a new one until you actually get your BOWP. Plus, you may not get provincial health care coverage while in maintained status—last I heard of it, it's at the discretion of the individual offices. So yeah, having applied for it gives you some rights and you absolutely should do it, but actually getting it is a lot better.