It's time for sth中sth指名词或与其性质类似的.比如“It's time for breakfast”
It's time to do to 后面只接动词原形.
同时It's time to do sth有强迫性的意思
而且to后跟的是动词原形：It's time to have lunch.
for后跟的是名词或动词的ing形式：it's time for lunch
it's time for having lunch