What is the ruling for a person who does not intend to offer a sacrifice until he can afford it which may be the morning of the day of 'Eid concerning trimming hair and paring nails? 

A person who was not planning to offer a sacrifice cuts his hair and pares his nails during the first 10 days of Dhul-Hijjah and then decides to make a sacrifice, must refrain from cutting his hair and paring his nails from the moment he makes his decision.

A person who does not plan to offer a sacrifice from the first day of Dhul-Hijjah and who decides to leave the matter until he can afford it, cannot be described as having the intention to make a sacrifice. It is not disliked for him in this case to trim his hair, pare his nails or shave any part of his body until he makes the decision to offer a sacrifice at which point it is recommend to refrain from doing all of the above.
And God Almighty knows best.