Is there such requirement? Let say you finish level 1 but you want to take a year off before doing level 2 and 3 for whatever reasons. Do you need to complete the whole thing within a specific time frame after you pass level 1?
There are no such requirement.
There used to be a 7 year limit but that was removed.
You can take 50 years to take the exams if yyou want.
Also, there’s no requirement to get your four years of experience in any amount of time, either. So if you pass the test in June 2013, but don’t get your experience (for whatever reason) until 2050, that’s okay. You can apply for full membership in 2050.