Nobody on the internet can tell you what lens prescription you'll need... go see a professional.
I don't believe that you can set the parallax correctly and have the image and reticle in clear focus if your eyes are not 20-20 or corrected to be 20-20 through glasses or contact lenses.
Yes you can adjust the ocular bell to get the reticle clear.
Yes you can set the parallax to get the target image clear, but that does not mean you are parallax free.
If you do not have 20-20 vision you will not be parallax free at this point, so you need to make a compromise.... Head bob to get parallax right with blurry image or get image clear but you will have parallax.
I recommend that you get prescription bifocal safety glasses from an optometrist.
Even with the prescription glasses and 20-20 vision, not all scopes are actually parallax free when the image is at it's sharpest, so you'll still need to apply the head bob technique anyway, if you want to shoot accurately.
Here's the good news... At least you'll be inspired to wear your safety glasses when shooting... as many people don't.