What will you use as work phone in the meantime? Can you survive without a work cellphone?
Personally, I wouldn't want to use my personal smartphone for work. I've got several unlocked phones (5c, 5s, Moto G) that the family uses for international travel which can be temporarily appropriated for work use. If I didn't have any spare phones to use, I'd just get whatever free model is more suited for my work usage.
I mostly work from home. I use my work phone to access email/tethering when I'm in route to a client site. Once I'm onsite, I usually have internet access. That's why I'm thinking I can hold out for another month. When fall kicks in though, I'll probably need to get something.