When the soil is only just workable and a cold spell is coming, I would rather wait than force the job. Planting into cold, wet soil can set plants back quickly because the roots are sitting in poor conditions before they have had a chance to establish.
The cue I trust is the squeeze test. If you grab a handful of soil and it crumbles apart, you can usually keep moving. If it stays as a sticky ball, smears, or clings to your boots and tools, the soil is too wet and you are better off pausing.
That short wait can protect the whole job. Working wet soil can compact it, damage the structure and create drainage problems that last longer than the cold spell itself.
If the plants are hardy and the soil is open, friable and draining well, you can push on carefully. But if the ground is wet, heavy and about to get colder, stopping is usually the more professional decision.