When you sign the Purchase and Sale agreement - you will need to make your 2nd deposit of escrow. Again, you can write a check or use the electronical deposit link offered from the real estate office.
Keep track of all deposits - you will need for the mortgage company. Make a folder in Google drive to put all relevant data in the folder. In case, you need data you already submitted but need to submit again.
Once the deposit check is deposited, mortgage process starts. Appraisal is ordered next. Escrow is held either at the listing agent's office or the sellers attorney.