Here are feelings which to some degree are related:
- The feeling of waking up in a new city for the first time or starting work on a new job.
- The feeling of new love, meeting someone for a date, getting married or having a baby.
- The feeling of imagining what will it be like being in some place or time you have only read or heard about.
I have always felt myself at a loss of words, trying to convey that sort of a feeling precisely. I have to throw in several words to convey the effect: anxious, dreamy, excited, nervous, fresh, overwhelmed and so forth.
In contrast, if I have to describe the sad longing associated with old things, I have a precise term, namely, 'Nostalgia'.
The closest one word I could think of was 'Forward-looking'. But I feel, it is a bit too positive. Another word that I would consider is 'Ambivalent', but it needn't necessarily convey the feelings of new beginning. There must be a better word, isn't it?