When should I file an expedite request for I-485/EAD?

[werrerr 17]

So I already have a job in the US on a H1B visa, and it is set to expire in August of this year (about 5 months left).

 

I did my biometrics last month, sent the RFEs for i-485, and I'm basically doing the waiting game at this point. Unfortunately, my I-765 was rejected twice because I put in the wrong category twice, and it twas only accepted in January of this year (I sent it in in November, and USCIS sat on it for ages...) So I think while both applications have a chance of being approved by August, I don't feel confident that either of them will definitely get approved.

 

I'm talking to my employer, and they told me that because I'm Canadian and the H1B quota isn't full, they won't file for an H1B extension (I don't really understand this tbh), and that there might not be another option. I feel like the HR isn't fully informed on i-485, because a google search shows that I can try to expedite my case. The only thing is, I don't think my case is urgent yet since I have 5 months. So I'm just wondering if anyone has experience with the expedite request, when I should file it, or if it's even worth it. Any help or insights would be greatly appreciated!