I already have two little ones of my own I have been ovulating since the 22nd of march and it is now the 24th of march and we had unprotected sex last night we want to conceive a little boy because we have two girls well I held my legs in the air for 30 minutes then I went to bed and I woke up this morning with some very light cramping and also I had a very light spot of brownish blood on the toilet paper when I wiped and I have never experieced that before so please someone tell me what this means I am so confused I hope this means the egg planted itself in my uterus... :p

If you had sex last night, the sperm hasn't even reached the egg yet. Thus, implantation has not occurred.

It takes about a week from the day of sex until time of implantation.

Then tell me what is going on please ? I did not think that implantation has happened yet but I'm not for sure so what is going on?

It just could be a little irritation from the sex is all. It's definitely not implantation, I can tell you that for 100% certainty. Maybe the sex got a little rough and your cervix was irritated, or there may be a small laceration in the vaginal canal. Really nothing to be concerned about. Quite common actually.

How long should I wait before I can take a pregnancy test to find out if I am or not? What is the earliest signs of pregnancy ?

The earliest sign of pregnancy is a missed period. You can safely test after that.

Having some spotting isn't uncommon at all, no matter what is going on in your life(pregnancy, using birth control, stress, being sick, rough sex, etc) brown blood is simply old blood. Most often its just from irritation of some sort, or some slightly disturbances in your hormonal balance(like the above reasons, being sick etc), but as J9 said, its definitely too early for this to be implantation from last night.(of course, whether sex is protected or not, pregnancy is always a possibility, so if you've been having sex before this, esp if you are trying to get pregnant, then it could have been from a previous sexual expereince) once you miss your expected period, wait a week. Once you are a week late, take a test with first morning urine. IF it is negative, wait one more week and test again. If still negative, wait for your next period. If that is missed, and the tests are still negative, its time to see your doctor. Other then that, its simply the waiting game.