You don't need to perform a dash. The dash is merely the option to cut the time from getting 43P to whiff on the invulnerable state from when they touch the ground. The only time you really need to input a dash is if you are trying to go for 33P+K. You can literally tap guard twice as a secondary option to cut the time and then 43P. Literally, you can just stand there, wait, and then enable 43P. Doing 43P too early will simply whiff so you have to wait, but there is a noticeable time frame on when you want to land 43P. Dashing isn't necessarily required, it's just a person's method to getting "their own timing."
The difference between 43P and 33P+K is that 43P's sidestep function puts him closer to the enemy for netting that right advantage. Doing 33P+K is sketchy since there is a large distance gap that can prove troublesome if you are aiming for setups after teching someone up. If you can't do 43P, swap to 33P+K after the dash. It's guaranteed even in AI standards. 43P is not even a true force tech, it's just a force tech that lands on the right frame from when they touch the ground, thus making it almost impossible to do wake up kick options regardless, but so does 33P+K after SPoD. Astro go for dash > 33P+K, but it's recommended to go for 43P since it puts him closer to the enemy. 33P+K however, is never bad. Don't ever feel shame for going for the older option because it still works.
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Also 64T's best FT option is 4PP+K. Never understood why 43P after 64T is a thing since 4PP+K is a no-timing tech with higher advantage.