Almost correct with V1 speed.
JAR certification gives a 2 second buffer or thinking time in which to start the process of stopping ie brakes/rev etc
FAA if I recall only allows 1 second, although that may have changed.
So if fire bell goes at exactly V1 the perf figures allow for 2 seconds in which to make your decision and start stopping
, so you will go above V1 and the figures have an allowance built in for this. Not much thinking time I'll grant you but it's there.
It also explains why types certified under grandfather rights have "better" figures than new types.eg 737 has 1 sec , 320 or newer types have 2sec so worse performance on paper but in reality a fraction safer.