Congrats Funny..... had my first child born in June so this is still fairly fresh in mind...
The first 2-3 months you might not get an awful lot done unless you wife is doing breastfeeding, wherin you get a free pass when it comes to feeding time, that is until her nipples get too sore & she is too tired and she resorts to expressing milk at which point you learn what 2 AM looks like when it's your turn to do the middle of the night feed.
Around 2-3 months things start to get easier when the little nipper sleeps thorough the night, so you don't feel like a complete zombie come 8pm when you would like to get some painting in.
On a slightly more serious note when the baby arrives take as much time off as you can manage to get. The wife will really appreciate the help, you get to bond with the baby and with both of you around you are likely to be less stressed which means that the baby will ( in my experience anyway) be calmer and less likely to be crying and whingeing. This makes the whole baby at home thing that much more pleasant and there is nothing quite like seeing your little one smiling and gurgling with happiness to put a big grin on your face.