Start pumping as soon as the baby is in sight, even if this means you will be pumping for 4 months. You do not have to pump frequently on a schedule. Do what is possible. If twice a day is possible at first, do twice a day. If once a day during the week, but 6 times during the weekend can be done, fine.
Partners can help with nipple stimulation as well.
This drug can help you produce more milk. It is not necessary for you to use in order to breastfeed an adopted baby, but it will help you develop a more abundant milk supply faster. If you do decide to take it, the dose is 20 mg four times a day. Check here for more information. Ask at the clinic.