No perfect timing...and you may try for that perfect "timing" and it may not work...lol We tried on our first "go around" for three years apart and it worked perfectly! Our daughter, and son are three years and 3 days apart. Then we thought we wanted just ONE more, three years later, so we tried just the same as we did before, but it didn't work the same and I got PG with TWINS and so #2 and #3 & 4 are two years and 4 months apart. The OLDEST daughter being nearly 25 now and the youngest daughter, 19, (boy/girl twins....so the girl of the twins) are NOT close at all and they are almost 5 years apart. The boy/girl twins are very close. Actually, all the kids are close, except the oldest and youngest daughter, I'm guessing it's the age gap, and female hormones? The boys do great with each other and with their female sibs. So, to answer your question, there is NO right or wrong age...just go for it and know they may have their times, but hopefully they'll all grow up healthy and happy!!!