Jacob was visiting while the island was flashing by sprovo

I began trying to make sense of the flashes. On the island they came off as random events and later was explained by the FDW not being on track.

I believe each time the island flashed that Jacob jumped to another time period in order to come in contact with the Losties that he came in contact with.

I know there were some other things that happened to the Losties while they were on the island during the flashes that seemed like fate. I believe they were fate like instructions for the Jughead.

If Christian is connected to Jacob then it's even more likely that Jacob used the FDW as a tool since Christian was down there helping Locke when he left the island.

You say Jacob didn't use the FDW to get off the island? Then please fill me in on your your idea of how he was leaving and then came back. We only know of him coming back once so he either was leaving and coming back each time or he lived in the outside world from the time he met Kate as a child to the time he met with Hurley in the cab.