This happened before the war.

Lucifer always spent his days making chores and following orders, that until his Father created the first two humans; Adam and Lilith.

Lucifer fell in love at first sight with Lilith, he often sneaked to the garden only to spend time with her… He had been doing that since quite a time now.

Lucifer was on his snake form, slithering around the garden while looking for Lilith.