So all of the dates are from the various ancient Egyptian calendars. I included some with just epithets listed which I thought pertained to Nut such as “Lady of Stars” and some may pertain to Hethert-Nut (Hathor-Nut) rather than just Nut.
Monthly Festivals
6th Lunar Day–Sacred to Nut
28th Lunar Day–Going forth of Nut
1st Akhet/Thoth/August
1-Wep Ronpet: New Year: Opening of the Year
4-Feast of Nut
7-Day of Welcoming the Rising of the River
11-Procession of the Great Flame (Eye of Ra)
13-Feast of Nut
14-Feast of Nut
14-Speech of Weret Hekau/Magician
22-Speech of Weret Hekau/Magician
2nd Akhet/Paopi/September
3rd Akhet/Hethara/October
3-Speech of Nut, the Great
4th Akhet/Koiak/November
4-Speech of Nut, Who Gave Birth to the Gods
21-Speech of Nut, the Great, the Mother of God
24-Speech of Nut, Lady of Heaven
1 Peret/Tybi/December
15-Speech of Nut
25-Establishment the Celestial Cow, Descent of the Dove
2 Peret/Mechir/January
30-Speech of Nut, the Great, Who Gave Birth to the Gods
3 Peret/Pamenot/February
8-Speech of Nut
10-Procession of Neseret
17-Speech of Weret Hekau/Magician
18-Feast of Nut, Who Counts the Days
19-Birthday of Nut
22-Speech of Nut, Lady of Heaven
4 Peret/Parmuthi/March
2-Speech of Nut
20-Speech of the Lady of the Solar Rays
21-Speech of the Lady of the Sycamore
1 Shomu/Pachons/April
3-Speech of Nut
8-Speech of Nut, Lady of Heaven
23-Speech of Nut
2 Shomu/Payni/May
20-Speech of the Lady of Stars
28-Speech of Nut
3 Shomu/Epiphi/June
15-Speech of Nut
23-Speech of the Uraeus
26-Speech of the Lady of Light
4 Shomu/Mesore/July
5-Feast of Nut, Speech of the Lady of Light
7-Speech of the Lady of Divine Liquor
9-Speech of the Lady of the Horizon
10-Speech of the Lady of the Mirror
18-Speech of the Lioness
24-Speech of the Lady of Heaven
Sources
Bakir, Abd el-Mohsen. The Cairo Calendar No. 86637. Cairo, 1966.
Brier, Bob. Ancient Egyptian Magic. New York: William Morrow and Company, 1980.
Cauville, Sylvie. Dendara XV: Traduction: Pronaos de Temple d’Hathor. Peeters, 2012.
Ellis, Normandi. Feasts of Light: Celebrations for the Seasons of Life based on the Egyptian Goddess Mysteries. Quest Books, 1999.
El-Sabban, Sherif. Temple Festival Calendars of Ancient Egypt. Wiltshire: Liverpool University Press, 2000.
Morgan, Mogg. The Wheel of the Year in Ancient Egypt. (Mandrake of Oxford, 2011), 177 and 208.
Siuda, Tamara. The Ancient Egyptian Prayerbook. Illinois: Stargazer Design, 2009.