Does invetro usually work the first time?

Hard to tell: In vitro fertilization is a successful way to fertilize the egg cell in artificial conditions. Whether it will work on the first attempt or not, it is hard to tell and depends on the viability of the product of conception and the environment it is embedded in. The fertilization itself may happen but the viability of the fetus doesn't depend just on the method of in vitro fertilization used.

IVF success rates: Ivf is not 100% successful but then nothing is. Normal fertility is 20%/month. The best ivf centers have success rates >70% in ideal patients <35 yrs old. If you add success from frozen embryos then 1 ivf cycle could give babies over 80%. The national success rate for women <35 is about 48%/ try. Many centers have refund guarantees so that you get most of your money back if no live baby.