Technical Question for Residence Visa Appointment

Dear Members,
I hope you can help me in this:

Our family has appointment for residence visa on 26th of October.   I am from Iran and usually I get 3 months visa on arrival for Turkey. My son is from Pakistan and he has 1 month visa.  We entered the country on 5th of August. Now we have been told we should wait inside country until the date of our appointment.   But in case we need to exit, we can; since my 3 months visit visa since I entered is valid is ok for me, but for my son I only have to pay some fine.  I just want to double check if this is true and if in case we exit the country the date of our appointment won't be affected as I don't want to lose my appointment date.
Please if anybody knows and can advise.
Many Thanks