My question: is there any benefits to waiting to amass more money before making a deposit? (Say making a bigger deposit of $300 every three months?)

Depends - there's a difference between depositing and investing. Depositing can mean that it's in the IRa so you can't spend it elsewhere. Investing means you've bought something within the IRA.

I manage my daughter's Roth IRA & she sends a $250 check to the brokerage every month. I don't necessarily buy something every month but the money stays in IRAville.

Also if you're starting now, mark the contributions 2003 as long as possible (check IRS pub 590 for the rules) so you have the full contribution available for next year, too.

rad