Timestamps 
SmartPy's type for timestamps is sp.timestamp. It corresponds to the timestamp type in Michelson.
There are two ways to specify a literal timestamp:
sp.timestamp(n)refers to the moment in timenseconds since the Epoch. For example,sp.timestamp(1571659294)represents 2019-10-21T12:01:34Z.sp.timestamp_from_utc(year, month, day, hours, minutes, seconds)represents the given time in UTC. For examplesp.timestamp_from_utc(2021, 12, 31, 23, 59, 59)corresponds to 2021-12-31T23:59:59Z.
- sp.now →
 The current block timestamp, a.k.a. the "minimal injection time". For a detailed explanation see Michelson's
NOWinstruction.