Do you know how often can cats get their shots?..?

I'm planning to take my cat abroad...but I don't know exact date of my trip yet. He has to be vaccinated (rabies shots) from 6 months to 4 weeks before the flight. But his vaccination is due now...Do you know if he can get his shots now and then the next ones that he needs for the trip in short period of time, like couple of months?Or there is obligatory time between the vaccinations??