Hi,
Six months sound a reasonable period to wait, unless of course you are having problems?
If you have fever, blood in your urine or are having pain in your back, loins and possibly belly, then you should see your doc before then.
Is your disease mostly under control? Your doc should be able to tell if everything is ok by blood work and possibly a urine dip. The blood work will tell him your Creatinine, Urea, Na+, Ca++ and K+ levels, so that he can alter any meds that he needs to and to further tests if needed as well.
Hope this helps?
Sarah