When a district court issues an order extending a filing deadline, it is usually safe to assume that your client will not be prejudiced as long as you file within the period ordered by the court.
However, consider the case of Charmaine Hamer. She recently lost summary judgment on an age-discrimination claim against her former employer and sought to appeal. Prior to the expiration of the 30-day period for filing a notice of appeal prescribed by FRAP 4(a), she asked the district court for an extension. The district court granted her an additional 65 days to file her notice. Hamer then filed the notice within the extended period prescribed by the court, and the case went up to the Seventh Circuit.