IMO to avoid being screwed over-You probably trust your staker but you never know
You should request that he pays the money upfront to play with.
You may have a few losing days and you never hear from him again since your playing with your own money
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As for your question. If i was him i'd set a date to end the stake. Or a cashout date. So that I'm not going to have to deal with splitting money every single day.
So lets say you guys put this at 7 days:
Day #1+400
#2+300
#3-500
#4+500
#5-600
#6+700
#7+100
This leaves us with a balance of +900
900/2(since its 50/50) You pay him $450 u keep $450 and tuck it away.
If you were ending the stake there for good youd also pay him stakeback-The initial stake he gave you.
You could always go your route and pay him everyday if that is easier for you. GL with the stake if you have any questions just pm me