i would like to know how many shifts a miner has to put in to achieve 500 n?
Well a shift is time based - not work based - so it varies dependent upon the pool hash rate.
You can see how long a payout is by looking at the Rewards page - you'll notice it's inversely related to "Pool N Avg"
That's the amount of time you have to be mining to get a Reward as high as your hash rate when that block was found.
Of course, that's simply at what point you have shares covering the whole payout.
Each share you submit will have attained all it's possible Reward by that amount of time after the share is submitted.
It's not a loss in BTC as you ramp up, it's simply how the Rewards are gained over time, not immediately.
... though you can compare that to a PPS pool also - you don't get 10THs of payments when you connect to the pool, you get that over 100% Diff of mining PPS
Here it's over 500% diff and also, of course, luck dependent.
The 500% reduces the variance and also makes sure most shares get at least some Reward (they all do except when a block is > 500%)
