Start Date of the Resource, start date of the Role

We are setting up the resources (importing from HR) and roles in Collections. Business concern - whether would be any problem if it is a new employee as a resource and his (her) start date as resource and roles is today's date (or pretty recent date) - would this resource be able to run dunning process and catch all transactions including the old delinquent ones? Also whether any collections related setup problems because of the recent start dates - any limitations Oracle has and these start dates better be in far in the past ?