If you're following the Pega guardrails, you're likely to be ok, but if you have any doubt, run your app tests for your particular application built on top of the Pega core rules. Some things I can think of to watch out for:
Whenever dealing with time zones in API and function parameters, use the official names rather than abbreviations. For example, don't just say "EST".
In contexts where a date-time stamp is appropriate rather than just a date, don't omit the time and assume it will be defaulted the way you expect.
Daylight savings time is well handled by java's libraries. Normally you shouldn't need to do much of anything other than double checking that the timezone datbase is updated properly. If you have been dutifully applying JVM patches, then you are likely ok. For more information search oracle's site for their TZUpdater tool and Timezone data.
This is also a good time to prepare calendar rules for next year!