Q.bloom time for baby’s breath
Planning an Oct 1st wedding. Will baby’s breath bloom till fall in S.E. Michigan?

Annual Baby's Breath will bloom one time, mid summer.
Perennial Baby's Breath will bloom for a longer period--generally also beginning around mid summer.
Depending upon the growing conditions and weather, the bloom time could go into the late summer or early fall.
You could cut and dry the Baby's Breath for your Oct 1st event.
https://www.gardeningknowhow.com/ornamental/flowers/babys-breath/growing-babys-breath-flowers.htm