A GENRAL POINT: These trades are not as rigid interms of times of entry as suggested by some of the posts above..(see Augens articles on SFO).
Report on AMZN and GOOG Trades.
Strategy 1.. (see Augens articles on SFO):On Thursday morning, When the share price is at ( or close to) an option point, Buy weekly fly centered at the relevant share price. Sell shortly before the close on Friday.
On Sep. 30, AMZN price was closest to 250 at 10:00 AM, so buy 245/-2*250/255 @1.02. Sell @ 1.20. near close Friday.
GOOG: price was closest to 685 at 9:55. Buy 675/-2*685/695 @2.48. Sell @2.67.
Both trades were potentially profitable IF you could buy and sell @ midpoint. However, bid/ask spreads were quite wide for all trades, so a considerable slippage was likely, reducing the profit.
Strategy 2: On Friday, when share prices are at (or close to) an option point price, SELL the weekly expiring fly centered at the relevant price. Buy back close to expiration, or when the price approaches the next option point.
AMZN: at 10:10 SELL 240/-2*245/250 @ 2.80. Buy at the close @1.60 . Could sell earlier @1.15.
GOOG: 10:35 SELL 675/-2*685/695 @6.65. Buy at the close @8.50. Could get out @6.50 earlier.
Clearly, AMZN trade very profitable, but GOOG very unprofitable, although the loss could be small if you are very nimble.