Behaviour in Pre-oestrus:

In pre-oestrus, initial signs of agitation may be observed in the animal. In addition, the milk yield may fall slightly and the genital region, especially the vulva, becomes swollen. Some animals rest their chins on other animals’ backs and hold their tails to the side. The flehmen response (lip-curling) may be observed. A vaginal discharge develops, thick at first and then becoming clearer and thinner.

It is still too early to inseminate. But the animal should be observed more closely from now on.