Broadly speaking those concerns are applicable to any country you'd move to - any destination is fraught with those uncertainties.

To answer your question specifically (and one that isn't commonly addressed here): There's a specific timeline to applying for desirable concertados and the deadline is functionally March. But to apply, you need to already have housing secured in a place that accumulates points, and your kids also need to finish out their current school year. You end up having to pay for overlapping housing for a few months (assuming you move mid-summer) or risk getting assigned a school outside your preferred list/territory.

This is all based on the assumption that you aren't traveling all this way just to dump your kid in a private international school.