The 5th metatarsal bear weight when u walk. So it needs to be protected till it heals.
Normally it takes 6 weeks to 3 months for the fracture
to heal depending upon the site, ur age, and any other associated medical problems that u may be having.
If on full wt bearing in the boot, u r not having any pain; then u can discontinue it after another 2 weeks. But do use a crepe bandage to prevent swelling.
Even then it is advisable to see ur doctor, who has seen ur x rays and know the personality of ur fracture; he will be able to advise u perfectly.