Hello Sandi
When the time is specified on your ticket, it must be respected. To be sure, I advise you to contact the Rail Service directly on 0041 (0)848 44 66 88 (CHF 0.08) or to go to a SBB station. All you have to do is give them your order number so that they can access your ticket visually.
I wish you a nice afternoon.
Regards,
JulieL