What date the visitor visa start from?

Hello

I am going to apply visitor visa for my parents and its the first time they going to visit UK. I was thinking to apply in October but I want the visa to start from December. Is it possible to get UK visitor visa for specified start date even though if I am applying couple of months in advance.

As its thier first time for applying UK vistor visa, can they still apply for 10 year or 2 year multiple or they have to do 6 months first and then next time they can apply for the mutiple?

What supporting documents should I send ?

Any information on this will be appreciated! Thanks

The start date of the visa can be postdated by up to 3 months - one of the first questions on the application form is "what date do you intend to travel to the UK?" Make sure that's filled in, and a covering letter asking for the visa to be dated for the day of travel would do no harm.

If this is their first application, I would concentrate on getting them a 6-month visa before thinking about 2-year or 10-year visas.