Hi,
Well everyone already covered the size of mouse ( hopper ) and Robin gave you advice regarding the F/T or live issue.
If you want to stick with F/t just make sure to pre-scent for an hour or so and heat it up just before offering - I like to use a hairdrier on the head for a good 30-40 seconds.
Evening/ night time would be the time I would pick to try.
If you do go for live remember to plan for a refusal too - a small critter keeper with a waterbottle, some food and bedding is a great thing to keep on standby.
Never leave a live rodent unsupervised with your snake though (unless its a pink or fuzzy unable to do any damage ). But if you use F/T you can leave it in the enclosure overnight if the lil guy won't strike feed despite the zombie mouse dance.
dr del