cross platform, do you want to time something or really get the actual time ?
var Tick, Tock : qword;
Tick := gettickcount64();
Something()
Tock := gettickcount64();
debugln('Something took '+ inttostr(Tock-Tick) + 'mS');
If you want the real time, call now(), there are a number of functions that will turn a TDateTime into what ever format you want.