Vaishno devi - Visit to Maata temple

Best season to go to Vaishnodevi
From weather perspective avoid winter -March, April, Oct are good
Large number of people go in Navratri, it is considered auspicious.
If you want to avoid rush go after Navratri espcially in April when weather is nice and rush is less too.
Weekend and long weekend has more crowds.
The journey can be little difficult in rainy season.

gallery jammu-katra-vaishnodevi official-website-for-vaishnodevi