Time spent on an UX is variable. The amount of time spent on research, writing the plan and recruiting users depends on the project/website. I've worked on projects In my training where the target audience was pretty obvious. Research time wasn't really necessary and recruiting users was easy because I knew just where to look for them. Writing your plan gets easier every time you do an usability test. You get better and you can use stencils from previous plans.
Based on my research following was my timeline
- creating persona - 16hr
- planning for research - 16 hr
- shortlisting the users who fit for personas - 30hr ( this depends on personas n requirement)
- user's (persona) interview - 12 hr
- preparing the report - 20hr
Reference : How Long Does a Usability Study Take from Start to Finish?