SS route temporary stamp 4 process

Hi All

I will be collecting my mom's passport tomorrow and hopefully it should have a letter asking her to get a temporary stamp 4 done. My question is - would anyone here have any guidance, tips, experience to share about the process?
Would be really useful for me to know if there is a right time to get to the queue, a right day for temporary stamp 4. How long should I expect to wait for between various queues and steps ?
Is there a parking area that you would be aware of ?

Thanks in advance.