Make Roth Contribution all at once or monthly

[rjpatt]

I just opened my Roth IRA and deposited 4k for 2006. I plan on depositing 4k for 2007 as well. Do most people on this board make a lump sum deposit in January or make monthly contributions to their IRA. I realize that by making a lump sum contribution, you are sheltering the money longer but monthly contribuions take advantage of Dollar cost averaging. Thanks for your help. I am only 20 years old if that makes a difference in the decision.