When should you first call a lawyer and involve them in the transaction? Does it depend on whether it is a resale or new construction?
In a resale situation you should ask your agent to send a draft of their standard offer to your lawyer for review and comment prior to even finding a house. Once you find a home you want to buy, your agent can send the proposed offer to the lawyer for fine tuning before it is submitted to the vendor. You are far better off having the offer reviewed prior to giving it to the vendors because, although you could make the offer conditional on review by your lawyer, that condition will slow the process and could result in you losing a property you really want because the vendors go with an offer that is not conditional on review.

Further, you don't really want to have to count on tracking down your lawyer at 10 o'clock on a Sunday night to review an offer you intend to submit. It just puts added pressure on you and the lawyer and increases the chances that something might be missed.

In a new construction situation you definitely want your lawyer to review the agreement before it becomes firm. In a new condo purchase you have a right in law to a 10 day cooling off period after you sign the agreement of purchase and sale.

However, in a new house purchase situation, you do not have an automatic right to have your lawyer review the agreement before it becomes binding, therefore you must ensure that the condition is added to the offer before you sign it because once you sign the offer it is binding and cannot be changed without the vendors consent, which you probably will not get.