Could Hitler launch Barbarossa earlier?

How likely is Hitler to attack the Soviet Union earlier without first resolving the other fronts?

Very unlikely; the railways, roads, and logistical preparation for Barbarossa could not be completed simply by choosing an earlier date.

An earlier eastern invasion is not a shortcut available at Hitler's discretion. Barbarossa depended on roads, railways, stockpiles, and other infrastructure that took time to prepare. The counterfactual makes those constraints worse by threatening Romanian oil and removing Scandinavian inputs. Germany might still attack later or choose another direction, but it cannot simply advance the historical timetable.