You go through these processes and eventually obtain your PhD if you can sustain the pressure.

Ambigious and hardworking stage, arrogant and complaint stage, confidence losing and hardworking stage and graduation.

Mimimum graduation is 2 years and very possible to graduate in 3.5 years. Put a date as reference only and enjoy your research.

Not healthy to fix a rigid time for PhD graduation. No difference as telling bf/gf that going to marry after 3.5 years dating. Who gurantee? Relationship should be stressful.