Greetings in the name of Jesus Christ.
I write this e-mail with great shame over myself. I committed fornication with a girl who was not my girlfriend and got her pregnant. The girl whom I got pregnant knew that I already had a girlfriend whom I was planning to marry and had already paid a brideprice for. We discussed the issue and I told her I could not marry her as I loved my girlfriend and with her it was purely a sin.
During that time I was not saved, and I used to have sex with prostitutes and with several other girls just for the fun of it. Every night, when I was by myself, I just felt lonely and would try find a girl to sleep with. This went on for a long time and even up to the time when I proposed to marry my girlfriend, who by the way is a Christian and is God-fearing. I got saved just recently and I confessed my sins to my pastor, who was also supposed to marry us. The pastor, however, now thinks that since the sins I confessed happened recently and that there is a pregnant girl involved, then we should postpone our wedding and wait for a period of eight months before we marry. I am confused now because I thought it was better for me to marry my girlfriend now than later.
There is no requirement for how long a person should wait until marriage. What the preacher has stated is his own opinion.
I must assume that the preacher isn't certain that you've really repented of your sins. He may be afraid that there might be other children that you don't know about yet (hence the eight months). He might also be afraid that you've picked up sexually transmitted diseases along the way.
When you get married is between you and your girlfriend. But I would be inclined to tell your girlfriend that she would be better off to wait a bit to see if you are genuine or not. My concern is that you did not value your commitment in the past when you were having sex with other women while dating your fiancee. I hope and prayer that you've made a serious and radical change in your life, but it would be nice to see evidence of that change.