assuming your offer is accepted, the contract to purchase will state the timeline for you to apply, get a commitment, and ultimately have the money at closing. You're Realtor/buyers agent should keep track of the timeline to make sure you comply with the terms of the contract.
You should always refer back to the contract for answers.
If you are unsure and not working with a Realtor, you should consult an attorney.
If you are not working with a buyers agent I highly suggest that you do. Or find a good real estate attorney. You will more than likely have many more questions throughout the transaction.
I do not work in the Grafton area but could recommend a couple very good Realtor buyers agents if you like. feel free to PM me.