Taking your temp alone will only be able to tell you when you have already ovulated. Women that have been temping for a while can usually tell from the pattern of their temps if ovulation is approaching, but this does take time. My advice would be to make sure you are checking your cervical mucous as well as cervix postion. This will give you a better indication of when you are approaching your fertile time.

If you are unsure of when you ovulate, you can try ovulation predictor kits, which will give you a bit of notice as too ovulation approaching.

Good luck