How 'on time' do i have to take my birth control pill in order to make it effective. + is taking it 40 minutes later than normal time ok?

Betterlatethan never: It is better to take the pill 40 minutes late than never. Seriously, you should try to take the pill at the same time each day, but within the hour is not a problem. If you fail to take it more than 24 hours later, the pituitary gland starts the ovulation initiation process especially with low dose pills and a back up method of contraception may be needed for the rest of that cycle.