No, with 250mg you will not feel anything within "4 days" or a week, not even libido unless you are severely hypogonadal beforehand. Those who say they otherwise are experiencing placebo.
Trust me, i can feel it in my dick within a week. But i'm talking about doing a real cycle with orals included. I can literally feel a difference in how my dick works, not so much libido, but it will get hard as a rock in like 3 seconds flat.
I still don't think 250mg is going to be worth the effort. Gains are all relative, i'm sure you can pack on some mass over a long period of time on that dose, but i guess it depends on your goals. For me, being on 250mg a week is just enough to keep my size, sure i make some little gains here and there, but it's nothing like being on 750mg of Test with some Deca thrown in.