Spontaneous Labor Only

Jessica • Expecting baby number 3 in May. Tandem nursing baby #1 and 2. Homebirther,lactivist,USMarine, non practicing doula.
If you had spontaneous labors, (no inductions please), in which week of pregnancy were your babies born? 
1st baby-38 weeks
2nd baby- 37+6
3rd baby- ???
Also, was labor faster each time?
Thanks!