One thing we know for sure is that "Guardians of the Galaxy Vol. 3" will take place after the events of the holiday special. The special sets up several plotlines that are likely to be further developed in the upcoming film. Since the special takes place after "Thor: Love and Thunder," which, as noted by Games Radar, takes place in 2027 (five years ahead of our own reality due to The Blip). That means the holiday special takes place, at the earliest, in late December 2027. Therefore, the earliest "Guardians of the Galaxy Vol. 3" could be set would be 2028.
We can further pin down the timeline for "Guardians of the Galaxy Vol. 3" if we look at the newly released trailer. We can see, for instance, that Groot is still in his Swole Groot form first seen in the holiday special, confirming that the two take place close together.
However, it's important to note that time is a loose concept in the MCU and isn't the franchise's primary currency when it comes to interconnectivity. "Guardians of the Galaxy Vol. 3" was initially supposed to be the first film in Phase 4 (a plan scuttled by Gunn's temporary firing by Disney and further muddled by the COVID-19 pandemic) and is therefore likely to deal significantly with the aftermath of The Blip. The fact that it can be moved back to Phase 5 without disrupting the MCU's continuity is proof enough that date stamps aren't as important as some fans may believe.
