He must have been able to grow his business quickly, because in 1628 "Willem Jansz op het Begijnhof" was mentioned by Samuel Ampzing as a noted "plateel" manufacturer.
The difficulties surrounding the secure dating and attribution of Dutch pottery of the 17th century has to do with the differences in manufacturing process and purpose.
Since most 17th-century Dutch earthenware was meant to imitate Italian or Chinese imported models, it is difficult to trace the various types to specific factories.
Most ovens for bread or pottery baking were situated outside city limits as a fire hazard, and when large quantities of waste material was created through process-related problems, these were generally disposed of elsewhere, being used as landfill for repairing dikes, for example.
For a long time the "grotesque" or "arabesque" faience now attributed to Willem Jansz Verstraeten was assumed to have come from the factories in Italy copying works from Urbino.