Welcome to the forum, and congrats on your new addition! Gotta love the name too, "Taco", it just makes you want to smile

We also have a rescue BFA, though he's been with us for about 6 years now and is a bit older than Taco (Kiwi is about 16 y/o). Theres actually a lot of BFA owners on here, so welcome to the BFA (Beautiful & Fabulous Amazons) club! We'd love to see some pictures of him!
Anyways, you are absolutely right that he needs some time. Depending on how much being caged/prior owners mistakes affected him, he could start warming up soon or later. That all depends on the individual. Our bird took several years to come out of his shell. Time and patience heals all wounds with these guys

So you know, ALL parrots, even the most bonded, loving, normally sweet ones bite on occasion. Doesn't matter how long you've had them or how much you love them/they love you, that's just an inherent quality of parrots. Luckily, amazons are pretty easy to predict (and avoid!) a bite from- watch their EYES and body language. When the pupils of their eyes dilate paired with a 'crouched' stance and flared tail, that is usually a good sign you better watch out. Zons also tend to do better with a firm and authoritative stance than other birds. If you aren't 'top bird' they will happily fill that role, and will rule the roost so to speak by using their beaks. While you should NEVER yell at a bird, if you are telling him to "step up" for instance, using a firm tone of voice with a confidently placed hand and body language usually gets better results than acting afraid or timid. I also strongly suggest stick-training amazons along with stepping up. Amazons are notorious for getting totally overstimulated at times (which translates to aggression) and that becomes a situation where it's better for everyone if the bird can ride the stick home or to their play stand to calm down. You may also want to look into 'bite pressure' training. One last thing, amazons tend to be 'one person' birds, and they pick the person. Unfortunately, your wife may simply never be Taco's favored person. That doesn't mean he cannot be trained to tolerate and even like her, but you can't force a bird to love you. Kiwi was *suppose* to be MY bird. Honestly, my hubby didn't even want a pet, but I begged and pleaded after my beardie passed and he caved. Naturally, Kiwi fell head over heels in love with my husband and I had to spend a long time (several years) working with him so he trusted me and wouldn't eat me. I did put in the effort, so I can now reap the rewards. I may not be his 'favorite', but we're 'good friends' and he enjoys hanging out with me while I'm cleaning and coming on walks/car rides with me, so I'm satisfied. Anyways, best of luck with Taco. Look forward to hearing more on his progress.