Spanish citizenship through descendant how long to be able to get EU

Just because Canada allows dual citizenship and Spain does not, it doesn't mean you get a choice on which countries' laws you must follow!  Spain ordinarily does not allow dual citizenship, so you would forfeit your Canadian citizenship.  It's not a "whatever" situation!  I believe you've already been told this on this forum.  Don't ignore it.

What EU "credentials" are you referring to?

@oceanstar343ex

As @romaniac indicates, there are no "EU credentials". A passport from any EU country (e.g. Spain) grants you "Free Movement" to all countries of the EU.

As part of the process of getting your Spanish citizenship, you would be required to renounce any other citizenship (i.e. Canada). Canada (like most other countries) does not automatically strip you of your citizenship just because you acquired another... you have to go through a formal process to give up your citizenship. I don't know the practical implications of you doing the first... but not doing the second (as Spain expects you to do). You'd have to do more research rather than assume it's no big deal. Certainly, I've decided against getting my Spanish passport for this very reason, even if I'm being overly cautious.

Personally, I think the value of an EU passport is overstated. My partner (like me, a TCN, Third Country National, in EU-speak) fell in love with the idea of a Spanish passport (and she has no downside, the Ibero-America exemption allows her to keep her Brazilian passport). We have jumped through a lot of hoops so she can qualify, and so far her citizenship application has sat in the big pile of applications for 2 years! I decided I couldn't be bothered (especially as I would have to renounce my UK passport), and I got my permanent residence permit last year. In reality, the EU has considerable protection for permanent residents: it's hard to lose this status once acquired, and most EU countries do have a streamlined immigration process for those with PR elsewhere. Not quite as easy as an EU passport, but not difficult either.