求助！

I am working for a big company now, but I don't feel I will get promoted any time soon, so I reach out for new opportunities and just got an offer from a middle size company. this new offer will bring me more than 20% raise on my current salary.

However, I am supposed to get my half-year bonus from my current job within a month, if I leave now, I am sure if I can still get it.

so, I am wondering if it is OK to start working for the new company without quitting my current job? I can use my vacations to stay with my current job until the bonus comes up, meanwhile, I can start my work with the new company after labor day?

Thank you for your suggestions.