Start and End Dates can be added to a process via the Edit Process Summary dropdown, on the Update Process page. This only affects an applicant's ability to start an application and is NOT a deadline to submit a form.
If you have entered a Start Date for a specific process, the ability for an applicant to start a request will begin at 12:00.00 AM of the timezone your site is set to. The process must also be toggled on in order for applicants to apply.
If you have entered an End Date for a process, the ability for an applicant to start a request will end at 11:59.59 PM of the timezone your site is set to. Meaning that the Apply button will disappear and if an applicant has not started a request by that time, they will not be allowed to do so.
Process Order on the Apply Page
Public processes will appear on the Apply page according to the order on the Available Processes list on the Process Manager page (not according to Start or End Dates). Use the six dots to the left of the process name to drag them up or down the list. Please note, Universe processes in SLM will always appear at the top of the Apply page.