Supermarkets must separate areas where alcohol is sold with a physical barrier from today.
While convenience stores will have to limit the visibility of alcohol as part of the Public Health (Alcohol) Act 2018.
It was the first piece of legislation which addressed alcohol as a public health matter.
Section 22, which comes into force today, provides for the separation and visibility of alcohol products and advertisements.
The act was signed into law on October 17th 2018.
It is aiming to reduce alcohol consumption, delay when young people start drinking alcohol and to reduce the harms caused by the misuse of alcohol.
A two-year transition period gave retailers time to comply with the new rules.
But Vincent Jennings, CEO of the Convenience Stores and Newsagents Association (CSNA), said there was a major delay in moving on the legislation.
He told Newstalk Breakfast the changes will take more time, due to a lack of consultation.
"There's no doubt whatsoever that a number of those 2,800 outlets that are licenced to sell alcohol will have changes, and you'll be able to see them.
"But others it will take a little bit of time because, even though it is two years in the making since the bill became an act... we attempted to make consultation with the Department of Health and with the Environmental Health Service almost immediately.
"And they held back until we concluded our discussions in August of this year.
"So it's only at that stage, because the bill was written without any reference to our own requirements for health and safety and for fire safety".
"There is no difficulty now - [but] it's just a matter of timing.
"There's only a certain amount of shop fitters in the country and we are working under a pandemic, so social distancing is required".
"It doesn't make sense, but it's law now and as such we'll go with this.
"But the thing I would like to say is none of this would have happened to the level of consternation that it caused over the years and the delays had there been early consultation.
"The Government is perfectly entitled to bring in policies, but it needs to discuss with all of the stakeholders how to achieve these ends.
"Not putting in a law and then trying to accommodate it".
A number of other sections of the act have been in force since November last year.
Section 14 prohibits advertising alcohol in certain places such as in or at a school, playground, park, train or bus station.
While Section 17 prohibits the manufacture or import of children's clothes which promote alcohol consumption or are branded with an alcohol product name.
And Section 20 prohibits the advertising of alcohol in a cinema - except immediately before or during an over-18 film or in a licensed premises in a cinema.