Hi Rajasjoshi 👋 welcome to the community forum! Thanks for posting.
Your first months bill starts from the day of your installation and will cover one calendar month. We also bill for services in advance. This bill will cover your 1st calendar month (from your installation date), plus your month in advance. From next month you’ll only be billed for a standard month in advance.
In terms of dates - when your services are installed / activated you’re assigned a billing cycle in our system. On average it can take 16 days to create your first bill, in which time you’ll have been receiving services from us. You are sent the first months bill as soon as it's generated.
You can find a really useful run through of your first bill, all the different types of charges and how they are listed in this help page 👉 https://www.virginmedia.com/help/virgin-media-first-bill . It should cover everything, but if you have any further questions or if you think there's something not quite right when you receive this first bill please let us know. We can then investigate and do our best to help. 🌞