According to the footnotes in The Life, Saint Teresa of Avila entered the Monastery of the Incarnation November 2, 1533, and made her profession November 3, 1534. Though scholars disagree about these dates,  Teresa undoubtedly entered the monastery and professed vows as a Carmelite nun.

When I took the habit, our Lord at once made me understand how He helps those who do violence to themselves in order to serve Him.  [Teresa seems to be referring to the terrible pain at entering the convent without her father's consent. See previous post.] No one observed this violence in me; they saw nothing but the greatest good will. At that moment, because I was entering on that state, I was filled with a joy so great, that it has never failed me to this day; and God converted the aridity of my soul into the greatest tenderness. Everything in religion was a delight unto me; and it is true that now and then I used to sweep the house during those hours of the day which I had formerly spent on my amusements and my dress; and, calling to mind that I was delivered from such follies, I was filled with a new joy that surprised me, nor could I understand whence it came.Whenever I remember this, there is nothing in the world, however hard it may be, that, if it were proposed to me, I would not undertake without any hesitation whatever; for I know now, by experience in many things, that if from the first I resolutely persevere in my purpose, even in this life His Majesty rewards it in a way which he only understands who has tried it. When the act is done for God only, it is His will before we begin it that the soul, in order to the increase of its merits, should be afraid; and the greater the fear, if we do but succeed, the greater the reward, and the sweetness thence afterwards resulting. I know this by experience, as I have just said, in many serious affairs; and so, if I were a person who had to advise anybody, I would never counsel any one, to whom good inspirations from time to time may come, to resist them through fear of the difficulty of carrying them into effect; for if a person lives detached for the love of God only, that is no reason for being afraid of failure, for He is omnipotent. May He be blessed for ever! Amen. (Life 4.2-3)

When I professed final vows, I did not expect to feel any different than I had because I’d been with the community for approximately 10 years already. I’d taken my first (“temporary”) vows 3 years earlier and figured that I’d already had the “vow experience”. I was looking forward to it and knew it’d be great, I just thought that it would be a confirmation of everything that had already happened.But surprisingly, the experience of professing final vows was different than anything else I had ever experienced. I felt ontologically (in my very being) changed, like my DNA was uncoded and re-coded with IHM. I felt like a new person, different, yet more myself than ever. The way I saw my sisters and my place in the community shifted too. This is one of those things that again is difficult to express but unmistakable nonetheless.With Teresa I can say, “I was filled with a new joy that surprised me, nor could I understand whence it came. Whenever I remember this, there is nothing in the world, however hard it may be, that, if it were proposed to me, I would not undertake without any hesitation whatever.” Blessed be God forever!