You know, I've heard from others here that your denim can indeed transfer color onto your vachetta. Just be careful until you get some patina on them and it should all blend in eventually, if it's not too bad.
Mine is about a month old - yeah the handles get dirty VERY easily. Use baby wipes if you have to. I try to use my arm to carry it instead of my hand whenever I can. I swear mine is already starting to patina.
If you want a real nice golden honey coloured patina, it takes about a year (in general). I remember when I got my first LV, I used solely that bag 1-2X a week for one entire year. However, if you use your bag DAILY, then you can achieve the same effect within 1/2 year. Of course, oxygen is the main factor and sunlight (heat) is the catalyst.
Also, I won't recommend baby wipes on brand new LVs cuz they're VERY drying and I don't know how you moisturize the leather lol.