part time job variable days social welfare question

my nephew has come across a position with a company but the position is part time variable days ,in other words, this week could be 2 days ,next week 1 or 3 days etc. depending on company demand ,
my question how would the above work with social welfare (payment) for the missing days not worked

The following is from the Welfare Website:

Part-time or casual work

If you get part-time or casual work (up to and including 3 days per week), you may still be paid a proportion of your Jobseeker's Allowance. However, you must show that you are trying to get full-time employment.
If you have been getting long-term Jobseeker's Allowance (over 390 days or 15 months) and you take up part-time work for less than 24 hours a week you may be eligible for the Part-time Job Incentive Scheme (PTJI). This scheme allows you to take up part-time work and get a special weekly allowance instead of your jobseeker’s payment.

People whose work pattern changes from week to week are known as casual jobseekers. Casual Jobseekers return dockets to their local SW office which indicate the number of days worked in the previous week(s).