Why did you take plan b if you are taking b/c pills?
But yes it should be fine to stop using condoms.
If you start your b/c piils on the first day of your period (first day of bleeding) then you are covered straight away, if you forget a pill or if you start them on any day other than the first day of your period then you need to use a back up method for 7 days.
Double check with the leaflet in your b/c pill box as some may have a slightly different guide - I think seasonale needs to be taken for 4 weeks before you stop using condoms (could be wrong I know one of them is like that).