We are talking about online accounts. Fidelity is same day ACH's for my CU. IIRC Cit Bank is not that fast.
ETA: Someone would have to do a t-bill sale to see the timeframe.
Schwab money fund current 7-day yield is 4.27%.
I bought a 1yr treasury ladder this week. 4 rungs (3,6,9,12 months) avg yield IINM was 4.68%.
A couple of weeks ago I got 1yr and 2yr out agencies at over 5%.
Schwab money market is the best I found (unless you go to jumbo size investments).
Outside of Schwab (in my E*Trade account) Vanguard was best ($3,000 initial minimum) followed by Gabelli ($1,000 minimum). Fidelity funds are lower, but do have the advantage of serving as a Core Position, which means any otherwise uninvested cash goes there automatically. No need to trade in and out.