Imagine this scenario
I am on holydays in France, I have been staying at my penpal's house for one week and tomorrow I am leaving to go back home (USA).My mother is supposed to pick me up at the airport but she does not know exactly at what time I am going to arrive .I am about to phone her when my penpal asks "What are you doing ?"I answer "I will phone my mother because she does not know exactly when she is picking me up at the airport tomorrow"
Shall I say "when she picks me up " because it is schedulded time so may be present will be better and may be future "she will pick me up".I think present continuous or present are the best choice because it has been already planned. What do you think ?