If Veda is timeless then when did the story between Saint Bharadwaj and Indra happen? As it is a story from the Vedas, when would it have taken place?

Many stories are found in the Vedas. Meemaamsa Shastra provides answers to such questions.
Some incidents happen in each kalpam (period); there is always a deluge at each kalpam resulting in another kalpam where the Veda emerges; the stories stated in Vedas happen in each period like the advent of Lord-s Rama, Krishna, and Narasimha.
The stories are like the Vedas – that emerge at various times; it has to be understood that what transpired earlier would have been stated in subsequent periods.