When you're younger your blood pressure doesn't really have to be checked all that often unless you want to check your blood pressure more often which is okay too.
Younger people can get by with checking their blood pressure once or twice every 2 to 5 years unless you have known high blood pressure.
Then if you have high blood pressure you should check it at least once per week or a few times per month.
I don't suffer from high blood pressure but I keep a check on my blood pressure every few weeks just to make sure my blood pressure is at it's normal reading which is 120 over 80.
However if your blood pressure is 135 over 85 that too can be normal blood pressure for some people but when it gets above the 135 over 85 then it's getting high and needs to be brought down.