We’re starting to do this with new members of our Lodge. There are a number of reasons - get the new brother used to public speaking, check out how well the initiation went from his end and, very importantly, get him thinking about what it means to be a Mason, reviewing in his mind what he has gone through, etc.
Remember - nobody expects profound Masonic wisdom from somebody who’s just joined. And keep in mind that every other person there will have gone through precisely the same ceremony, felt precisely the same mix of awe, confusion and information overload. In one sense, they will be reliving their initiation through you. Short of copious drooling or explosive profanity, you will not - cannot - mess up.
Just say why you joined, what it felt like at the time, what you feel about it now, etc.