Answer
Recently
Step-by-step explanation:
That time of year thou mayst in me behold = In me you can see that time of year
When yellow leaves, or none, or few, do hang= When a few yellow leaves or none at all hang
Upon those boughs which shake against the cold= On the branches, shaking against the cold,
Bare ruin'd choirs, where late the sweet birds sang= Bare ruins of church choirs where lately the sweet birds sang.