I cannot see a prosecution based on a breath sample taken after someone gets home being successful.
In fact, police officers themselves have been aquitted claiming they drank after getting home. Monty Robinson was famously convicted of obstruction after killing someone but not for impaired driving. He claimed he went home and had vodka.
In most jurisdictions police are far too busy to go hunting people down after vague complaints about bad driving.
I got hit by a drunk, chased the guy, Called 911 and told them, despatcher said they were "too busy, just get his plate and call MPI."
That shows how much priority this has.