Briefly: Frodo & companions leave Bag End on September 22, and reach Rivendell just under a month later (Frodo awakens on Oct 24). The Fellowship departs Rivendell on Dec 25 and arrive in Lorien in the evening of January 15. They stay a month and leave Lorien on February 16, the battle of the Pelennor and Frodo's escape from captivity happen on March 15th, and Barad-dur falls on March 25. These are all dates according to the Shire-reckoning, but the span of equinox to Christmas/solstice to Lady Day/equinox/Julian New Year was not an accident.
The Hobbit begins at the end of April, Thorin & Co are in Rivendell at midsummer, they reach Lake-town on Bilbo's birthday (Sept 22), and the death of Smaug and the Battle of Five Armies occur *probably* in mid- to late November (Tolkien's pretty vague on this, and doesn't seem to allow enough time for Bilbo and Gandalf to reach Beorn's hall by Christmas).