Ryanair said it will delay plans forcing non-priority customers to place any second larger carry-on bags in the hold to allow passengers "more time to familiarise themselves with the changes".
The airline was due to introduce the changes aimed at speeding up boarding and eliminating delays from next week but will instead implement them from January 15.
Ryanair cut its checked bag fees to €25 from €35 - at a cost of €50m a year - and increased checked bag allowance to 20kg from 15kg when it announced the changes in September in a bid to reduce the volume of carry-on bags.
It said at the time that too many customers were availing of changes introduced in 2014 - when the airline moved to rid itself of a reputation for poor service - which permitted two carry-on bags free of charge.
Priority customers who pay an additional €5-6 a flight will still be able to bring two carry-on bags on board from January.
More than 700,000 passengers due to fly between September and March were hit by the wave of Ryanair flight cancellations after problems with its pilots' roster.
Ryanair will report its second-quarter financial results next week.
It said in late September that average fares were expected to be slightly lower over the following two months as it promoted seat sales.