Time words in Chinese are normally placed in one of two positions in a sentence: /before/ or /after/ the subject.
現在她去學院還書。
Now she is going to the college to return books.
or 她現在去學院還書。
常 and 常常
常 in the sense of "often" can often be reduplicated as 常常 without a change of meaning. Thus, 他常喝茶 = 他常常喝茶, 我們常去看書 = 我們常常 去看書.
In making negative sentences, however, 常 is normally /not/ reduplicated. Hence 他不常喝茶, 我們不常去看書.