Phone upgrade: outright or finance?

Hello frugal friends! I am typing this to you on my iPhone 6s from 2015 which I purchased outright and have gotten a good 6 years of use out of. I think I can likely get a solid 6-12 more months out of it hopefully, but I need to start planning for getting a new phone!

I had originally decided I'd put away about $80 per month (when I am able to as this is beyond my means) so that I have some emergency funding for when this phone dies. However, after doing some research, apple has 0% APR financing plans for about $45/month for 2 years.

I'm trying to decide if I should take advantage of that now / soonish (likely when they release the 13 bc I'm hoping the price on the 12 will drop slightly), or continue to save to do this next year or in two years when I have the money saved.

If I buy it now with the financing plan, overall my monthly expenses are lower than if I save up for it and I could possibly trade in my phone and get around $60.

If I keep mine now, I will be saving double the monthly fee and planning to use this phone till it is completely finished.

But I don't want to make an impulse purchase just because I'm tired of my phone lagging (even typing this post is painful) and dying when I could deal with those issues, you know?

Thoughts?