I hope, it is not too late
I have done it like follows: I have load your week and Turnover in an Inline-Table called table1.
week, turnover, week-1 AS pre_week
week - 1 AS pre_week
left join load
week AS pre_week, turnover AS pre_turnover
Then you can sum in an pivot or sum table the turnover, the pre_turnover. For the delta you could use if(sum(pre_turnover) <> 0, Sum(tunrover) - Sum(pre_turnover)).