Harry and the other sixth years take their first Apparition lesson, under watchful eye of the Ministry instructor, Wilkie Twycross. None of the students manage to Apparate in this first lesson, although Susan Bones does manage to Splinch herself (HBP18). The lessons will continue for twelve weeks.
The first lesson was scheduled for the beginning of February on a Saturday morning. The first Saturday in February in 1997 is the February first.
Since the lesson happens in the morning and the tables have been cleared away, it appears to start somewhere between 9 and 10am.
The lessons repeat for a total of twelve lessons. Twycross says that the next lesson is on the following Saturday as he is leaving:
But an hour later, Susan's Splinching was still the most interesting thing that had happened. Twycross did not seem discouraged. Fastening his cloak at his neck, he merely said, 'Until next Saturday, everybody, and do not forget: Destination. Determination. Deliberation.'
If the lessons are weekly, the full course of twelve will run into May with a couple of weeks of for the two-week Easter holidays.
Ron's birthday, March 1st, occurs after the first three lessons:
Three lessons on, Apparition was proving as difficult as ever, though a few more people had managed to Splinch themselves. Frustration was running high and there was a certain amount of ill-feeling towards Wilkie Twycross and his three Ds, which had inspired a number of nicknames for him, the politest of which were Dog-breath and Dung-head.
'Happy birthday, Ron,' said Harry, when they were woken on the first of March by Seamus and Dean leaving noisily for breakfast. 'Have a present.' (HBP18)
Apparently, it's possible to test out before the end of all twelve lessons. The first test date, for those who will be seventeen by then, is April 21st.
There had been a certain amount of excitement earlier when they had come back from dinner to find a new sign on the notice board that announced the date for their Apparition Test. Those who would be seventeen on or before the first test date, the twenty-first of April, had the option of signing up for additional practice sessions, which would take place (heavily supervised) in Hogsmeade (HBP21).
The practice sessions take place on a Sunday two weeks before April 21, which we'll make April 7th based on the actual calendar of 1997:
And so the following weekend, Ron joined Hermione and the rest of the sixth years who would turn seventeen in time to take the test in a fortnight ... As it was Sunday morning, nearly all the students were inside their various common rooms, the Gryffindors in one tower, the Ravenclaws in another, the Slytherins in the dungeons, and the Hufflepuffs in the basement near the kitchens (HBP21).