If you sign a contract with (big contractor) mid January but they've delayed your mobilisation date by 6-8 weeks... Should you be paid for that time?

If contractual agreement for start date then yes but check fine print to see if there is a clause for dates to be changed without notice ets to cover their butt. If no contractual agreement and only a verbal then don't like chances

Yes if you signed a contract to mobilise on a specific date and they push it back they should pay you stand down pay think its about 7.2 hours a day 5 days I know a guy on my site who was payed this for 3 months for doing nothing in Perth because there wasn't enough accommodation on site