Jennifer Dulos’ bumbling, estranged husband and his girlfriend handed cops the “big break” in the case — and just in the nick of time, a law enforcement source told The Post on Tuesday.

Fotis Dulos had his cellphone with him and turned on when he and gal pal Michelle Troconis allegedly dumped incriminating items stained with Jennifer’s blood in Hartford, Connecticut, trash cans the night of her disappearance, court papers show.

And the phone pings led cops to discover that the pair had made more than 30 stops to toss the bags while driving on Albany Avenue — allowing detectives to collect crucial evidence in time, the source said.

Many of the discarded trash bags had already been hauled off to the area’s incineration plant by the time authorities learned last week of the pair’s movements, another law enforcement source said.

Police frantically had the incinerator shut down and learned that the sought-after trash collected from Albany Avenue may not have been burned yet, according to the Hartford Courant.

Police cadaver dogs have been scouring a massive mound of garbage there — crushed into fragments no bigger than 6 inches — searching for things such as bone fragments.

“Right now, it’s a mystery where she is,” the first source said of Jennifer. “We don’t have a strong lead.”

But some of the bags dumped along Albany Avenue were recovered from their bins before being hauled off, helping detectives finally bring charges against the suspects for alleged evidence-tampering and hindering prosecution.

Troconis allegedly did herself in by being caught on one of the videos leaning out the window of Fotis’ pickup truck, where garbage bags were piled in the back — to smoke a cigarette, said the first source, a Connecticut cop involved with the probe.

Jennifer, a mom of five, was in the midst of a bitter divorce and custody battle with her estranged husband when she vanished early May 24.

Authorities have said they believe she was battered in the garage of her home in New Canaan, more than 70 miles from Hartford, after dropping her kids off at school.

New Canaan police Monday sent an email to residents and also left a recorded message on their phones asking them to save any surveillance footage they might have related the case.

It took authorities a week to use the pings from Fotis’ iPhone X to guide them to the Hartford surveillance video and trace the suspects’ alleged movements, sources said.

Cops contacted the municipal trash facility near the Hartford-Brainard Airport on Friday, and the plant was able to determine which of its two trucks had hauled garbage from Albany Avenue after the alleged dumping, the second source said.

The new details in the case surfaced as Jennifer’s mother filed for at least temporary custody of her daughter’s children — while the kids’ dad was indefinitely ordered by a judge to have no contact with them.

Lawyers for Fotis and Troconis did not return requests for comment Tuesday.

Additional reporting by Natalie Musumeci