It’s smart, you can choose your words mid sentence while having already started the sentence, but it’s also not what you wanted to say. I would advise you to say what you want to say regardless off stuttering. I think what your doing is using cheat words. It’s not a bad thing but being able to say exactly what you want to say when you want to say it would be wonderful, right? My advise: write down every word you feel are words you get stuck on. See what letters the words begin with or just the sound of the words and make a list of acronyms. Repeat these words on a daily basis alone and out loud. Sing these words, use them in sentences and use them on purpose when talking with someone. What we’re trying to do here is re-wire brain pathways to saying these words fluently. It may seem stupid to talk out loud when there’s no one around to hear you but it will definitely help when people hear you since you are now familiar with them. Tip 2: before the word comes up you know you will get stuck on, pace yourself.. take a deep breath out and when you breath in right at the top of your breath right before you exhale, hit that word solid and continue with your sentence