The format I set out below is what I learned in Toastmasters. Toastmasters is a huge international organisation and there is probably a club near you. https://www.toastmasters.org/ They are a great relaxed forum for both learning how to prepare a speech and for learning how to give a speech.
But never mind. The wedding is only days away and you still have not written the speech and it does not look like you have time to join Toastmasters.
The key is to remember that every speech should have a beginning, a middle and an end and each of these will have roughly 3 parts.
I find it easiest to deal with the middle first. This is the bulk of the speech. You need 3 points or 3 anecdotes. Fine if you can only think of 2 to start with. If you have 4 and are aiming at a 5-7minute speech I would cut it back to 3.
The next step is your opening. Your very first line. You need to get their attention. A quotation. An outrageous statement. A couple of lines as to how you came to be there today. Perhaps refer to something that is going on in the world. Or ask a rhetorical question. The important thing is to start the speech with a bang. Get the audience’s attention.
The next part of the beginning is to address your audience. Thank them or thank whoever gave you the opportunity to speak. Address them direct.
Then the transition as you lead into the middle section. If you listen to the radio you will hear lots of good, and some appalling, transitions, as the presenter moves from one topic to another. Explain what you are going to talk about in the Middle.
This is simply the beginning in reverse.
Start with the transition. That’s enough about…. I have told you about…. Maybe give a summary or add a key point.
Then thank your audience or bring their attention to the key points that you want them to remember. Don’t worry about repeating yourself.
Then end with a bang. Perhaps reflecting your opening statement. This will give a symmetry to your speech.
For a five to seven minute speech you need about 750-900 words.
And practice, practice and practice. The more you practice the more it will appear natural, as if you have not practiced.
Don’t be nervous they are all on your side. No one is going to cross question you.