Thank you for your kind comment @pjcswart . Glad I could help. :)

I buy upvotes on day 6, but 12 hours before 7 day past. The reason is that on day 7 I get my payout. If I buy as close to day 7 then I don't see that much fluctuation in steem price and payout to me. I don't see my money in the system to long and can us it for my next upvote purchase.

We get paid on the 3.5 day moving average of the steem price. So if I buy close to day 7 I don't have the risk of wild changes in my rewards. The upvote sellers demand that you buy upvote not later than 12 hours before 7 days has past from post time.

Let me know if I am not clear on my points above.