It's actually a caution. I know you're eager, but you need to read the rest of that paragraph (this is actually a thread from last year.) Hurrying during early filing season gets many users in trouble each year. Since the IRS is not even processing returns yet, the early- efiled returns are stockpiled and sit on TurboTax servers--this year until January 29 (except for a few test returns.). So users who efile before the IRS is ready on January 29 will not get their refunds any faster. And all the helpers in the forum caution against the potential pitfalls in early filing season.
The early-efiled return cannot be retrieved when many users suddenly remember another W-2 or 1099 they are supposed to get or one arrives unexpectedly in the mail, or they notice they forgot "this and that" on their returns. In that case one has to wait until the IRS accepts or rejects the return after January 29. If rejected, the user can correct the return, make additions, etc. and resubmit. If it's accepted, however, the user would have to first receive the initial refund, then prepare an amended return which can be a hassle and takes several weeks to process.
