TRV for parents: processing time from Iran and proof of return

[ali_manu]

Hi all;
I am applying for my parents to get a TRV from Iran. Does anyone know how long it will take to process their TRV if they submit their documents to Ankara's office?
Also, I wondered what documents would be required for their proof of return? Are the bank statements showing they have accounts in my home country sufficient? Or should they provide additional documents such as residency?
Thanks