The following timeline is for your senior year in high school...
September
SAT/ACT prep-course
Check university requirements
Check for graduation requirements
Look for scholarships
Letter of Recommendations
Personal Statement
October
Obtain Financial Aid information
Apply for the Universities
November/December
Apply for housing accommodations
January
Income tax
Prepare transcripts to be send to the Universities you applied to
March
Take AP exams
April
Make your final college decision
May
Send your final transcripts to the college you picked
June
Attend orientation for the college you picked