Preliminary contract for land purchase

You can possibly clarify that carefully if needed! But basically it doesn't matter as long as the purchase for October is contractually sealed watertight by the notary. If you basically agree on that, I think I would either ask directly or take the following approach:

- Contact the notary to discuss possibilities of a preliminary contract, etc.
- after this conversation, or if he is involved, you can ask and refer to the notary or the notary brings it up
- either everything is clarified and you can buy immediately or for October

I bet the seller only has half-knowledge and was "transferred" the property by his parents = deadline long expired

For the speculation period (Section 23 Income Tax Act), the two dates of the mandatory legal transactions apply. So the dates of the notarized purchase contracts.

I bet the seller only has half-knowledge and received the property "transferred" from his parents = period long expired

I believe that too. Therefore, you should clarify that first!