next_meeting.rb

require 'benchmark'

# This takes like forever because '+=' adds seconds, not days.
bm = Benchmark.measure do
  next_meeting = Time.now.next_month.beginning_of_month
  while next_meeting.strftime("%a") != "Thu"
    next_meeting += 1
  end
end
bm.real
# => 2.02875781059265
# => 2.02947306632996


# This is what we want to use, 'advance'
bm = Benchmark.measure do
  next_meeting = Time.now.next_month.beginning_of_month
  while next_meeting.strftime("%a") != "Thu"
    next_meeting = next_meeting.advance(:days => 1)
  end
end
bm.real
# => 0.00124406814575195
# => 0.00165700912475586


# While we're at it, we can skip the loop
bm = Benchmark.measure do
  next_meeting = Time.now.next_month.beginning_of_month
  index        = Time::RFC2822_DAY_NAME.index(next_meeting.strftime("%a"))
  advance      = (4 - index) % 7
  next_meeting = next_meeting.advance(:days => advance)
end
bm.real
# => 0.000564098358154297
# => 0.000573873519897461