The only thing you'll need to change the patronymic is reaching the age of fourteen. From this age to change the middle name you may want at any time.
According to the law, an application to change patronymic would be considered within one month from the date of its submission. Only in exceptional cases, the visa processing time may be increased, but not more than two months. You have to inform in advance.
If you are between 14 and 18 years, to change the middle name, you will need the consent of both parents or guardian (guardianship and custody).
To change the middle name you need to contact the Registrar's office. Please bring with you the following documents: 1. birth certificate;
2. an application to change patronymic;
3. certificate of marriage (if you married);
4. certificate of dissolution of marriage ( if you want to take your premarital surname in the context of divorce);
5. birth certificates of your minor children (in order to make appropriate changes to their documents).