Hi if they have decided to remove your teeth in more than one session they should have discussed this with you. Contact them and ask whatever you need to know. You should decide how you want the extractions doing whether it is all at once or done in stages.
They should discuss with you the treatment plan including how you are to going to replace the missing teeth. Are you having a denture ?
The time left between extractions can vary and it really is something you need to contact them about. If you had all the teeth extracted then a denture could be made beforehand and placed at the time of extraction so that you have teeth to eat with and also they would help shape the gums.
I hope this helps a bit and you do need to contact them to know more about what is going to happen and when, it is your mouth and you are in charge as to how this goes. They are there to advise you and act in your best interest.
I have just looked at your profile and see that it is eight teeth being extracted, there is no reason why you can't have all the teeth extracted and a denture made to be fit at the same time. Even if at a later date you are having implants this can be done.