As you may know, the Dutch Tax Authorities (DTA) take 12-16 weeks before they decide on 30% ruling applications (once decided the DTA decision will have retro-active force to the date as applied for)
Not only the DTA have serious backlogs
In the past, the standard decision period of the IND on highly skilled knowledge migrant residence permit applications has been 2 weeks, when submitted by a recognised IND-sponsor. The current standard decision period for a (duly and complete) application for a knowledge migrant and accompanying family members, is now 3 weeks. Therefore, this extended 3 week decision period may influence the starting date of employment.
Furthermore, normally, the IND aims to take a decision on the application for the recognised sponsorship in four-six weeks. However, due to the many applications and backlogs at the IND, they are currently using the statutory period for making a decision of three months.
Should you wish to employ your employee as soon as possible, but there is no recognised IND-sponsorship available yet, you could choose the payrolling option offered by one of our network partners (such a payrolling company is already recognised sponsor by the IND), and may be the necessary to have your (non-EU) starting in the Netherlands without undue delays.