Before ownership is entered, the tax preconditions must be met. For the entry you need either a tax clearance certificate from the tax office or proof of the self-assessment by the contract drafter. This confirms that the real estate transfer tax has been dealt with. On a sale the property income tax may also arise, which the seller bears.
In the time between contract and registration you as a buyer hold an expectant right. It is the secured prospect of acquiring ownership once the entry takes place. The expectant right is more than a mere claim, because your position is consolidated by the contract, the declaration of consent and, where applicable, the notation of priority ranking. More on this in the glossary on the expectant right.
So that the expectancy also becomes ownership, all steps should be coordinated with one another. This applies to the payment of the purchase price through an escrow agent as well as to the land register application. How handling through escrow secures your acquisition you can read in the post on paying the purchase price via escrow. An overview of the review points is given by the focus page on the purchase contract review.