Depending on the pace of individual. It may be few years. However, the 3 attempt rule applies. Meaning, if you do not complete the part within 3 years (Part 1), you will need to restart from all 6 subjects.
Which means, if you have done 6 subjects by failing some papers and unable to completely pass all 6 papers within 3 attempts in 3 years, the 4th year you will restart from fresh/new – all 6 subjects from start.