re: Vanguard Roth IRA help

You opened an account (which you can do with as little as $1) but it isn't invested in anything yet (this is less to OP and more to responses). Many of the things you can/should invest in will have minimums of $1,000 at least and you can invest as little as $1 additionally once you've got an initial investment in a fund.. so investing each pay period is possible.

Yes you should max it out if you can do it comfortably (take out the difference from saving account).

You can contribute to Roth for 2016 up until tax day in April 2017 so don't worry about trying to max it out before December 31st.

I'd just add money to the account until you get $1,000 and invest in a market index or S&P 500 index fund (assuming $1,000 is minimum for those as well) as opposed to a target date retirement fund. Then invest a portion of each paycheck going forward.

ETA: Putting money into the account counts as contributing to your ROTH IRA for the year even if it isn't invested in anything. I'd avoid investing any money in a ROTH that you think you'll need in the near future. I know that isn't a black/white rule as some people do withdraw from their ROTH for certain things but I'd consult somebody who knows what they're talking about (i.e. not TD) if you end up needing to do that in the future.