In the slapd.env, there is a paramater called TZ. You can change this parameter to fit your local time.
The values are:
# Set timezone (Examples are EST5EDT, CST6CDT, PST8PDT)
e.g. TZ=EST5EDT or any other value like above.
# But it also accepts other format like GMT+/-xx
EST5EDT stands for Eastern Standard Time, 5 hour, Eastern Daylight Time
CST6CDT stands for Central Standard Time, 6 hour, Central Daylyght Time
PST8PDT stands for Pacific Standard Time, 8 hour, Pacific Daylight Time