Lets say a week.
to pay bills, service debt, invest in expansion, I would like a 95% confidence interval I will make 90% of my expected earnings for 2 PH.
Visit : https://ckpoolmonitor.zachmonroe.com/
to see off site computed numbers on actual payouts.
Reference: 1TH computes to 0.00418972 btc/day at current difficulty. (0.0044 last diff)
if 90% earning over a full week is your targets, the numbers there should help you with more info for making your decision.
"The pool hash rate for the last day is roughly 12.94PHs which means the 5Nd 'ramp' is roughly 2days 7hrs."
after 2.5 day, 90% looks very stable over a week period (from this angle).