Most people seen to recommend practicing the speech loads, which makes sense, so I'd try that. I do it a bit differently though, so this might be worth a try if that option doesn't work: I try to learn the content really well, and have a rough plan for each slide/part of my presentation, but not actually have a set speech. That way I know enough that I can freely move through the presentation without too much anxiety. It also helps if it's an interactive presentation where people will ask questions during it (so you'll be confident to answer, and it won't feel like their question is "interrupting" your prepared speech). The reason for this is, I feel like I mostly block/stutter in a sentence when my brain knows a tricky word is coming in advance. So if I'm reciting a speech, I'm going to know every word in advance. But, if I just know the content, and "wing it", I'm coming up with each word of my sentence only seconds in advance, so my brain doesn't get a chance to panic about an upcoming "tricky" word. This might just be specific to me, but it's worth also trying it. Aside from this, there's speech writing tricks that some stutterers use. I never tried it but I heard Joe Biden saying he writes his speeches in "blocks" of a few syllables each, and breaks these up with // symbols. He puts the // wherever he knows he can pause without stuttering, so always before an easy word. That way the tricky words are always in the middle of a block and you can flow into them easier. Worth looking into this more as I could be remembering it wrong. Best of luck!