New on the job and scheduling/leave

Hi everyone, I'm currently searching for a job and I have 3 days (fri, sat, sun) in January I plan to take a trip. If I get hired will my employer let me have these days off? what I'm asking is can the scheduling be done so I don't work these days or would I be asking too much being a newbie? Also how soon after getting hired can you take leave? Should I just be upfront w/ employers that offer me a job that these 3 days in jan I would like to be off?? I need to know if I can schedule this trip now. Thank you!