Q: Can one keep the first Shawwal fast immediately after Eid and then continue the other five during the course of Shawwal or does one need to keep two and then continue the rest during Shawwal?
A: You may keep the six fasts of shawwaal any time after Eid, immediately or days later, consecutively or intermittently. All ways are permissible.
Mufti Siraj Desai