Timeline for Transfer

[TycoRossBrewing]

So I brewed a Double Chocolate/Double Coffee Stout last week and have yet to transfer it to a secondary fermentation vessel because I had to purchase more rubber air lock caps for my glass carboy, my question is, if the krausen layer fell about three days ago, how long do i have before i must transfer it to the secondary? Will the beer go bad if I did not transfer it to the secondary immediately after the yeast layer settled? What is the timeline here for me to transfer from the primary before its too late?