In archaic|lang=en terms the difference between timely and available
is that
timely is (archaic) in good time; early, quickly while
available is (archaic) having sufficient power, force, or efficacy to achieve the purpose; availing, effective.
As adjectives the difference between timely and available
is that
timely is done at the proper time while
available is such as one may avail one’s self of; capable of being used for the accomplishment of a purpose.
As an adverb timely
is (archaic) in good time; early, quickly.