i don't have first hand experience if this is effective but maybe this can help.
1. give an overview of your relationship
2. state what job/business you have now. how much you earn annually. how long have you been working there.
3. state a suitable accomodation for you two i.e. letter from your landlord. deed of sale if you own it.
4. reasons why you are inviting her and why did you choose those timeframe.
