"In-year" school admission

Hello everyone,

I am from Bulgaria and I am in the UK for almost 2 years. Two months ago I brought my daughter to live with me in London. My daughter is 15 years old and we filled "In-year application" for school in the council. We are waiting 2 months already.

Last week we received a letter from the council which says that they have submitted my daughter's documents and now we have to wait for response from the schools directly. We already received answers from two schools but there are no places available, and their waiting lists are significant. Can you tell me how long does it take to start school when you are starting school in the middle of the year?

Thank you in advance!