Your first year you'll gross about $2,500 a month. That's a loose estimate based on being issued mandatory overtime 1 time per week. Depending on which station you're at it will vary. If you're at a winter weather station, you might very well be given mandatory overtime 3-5 times per week and in that case you'll make over $4,000 a month.
Your first year (between the first and 6 month step averaged) your hourly pay is $10.71. Times 8 = $86 per day. Times 11 (days in a pay period) = $942. Times 2 (pay periods in a month) = $1,885. But with mandatory overtime (which is a staple of all first year employees) you're payed at a rate of double time. Assuming you work even 1 mandatory shift a week that's $21.42 x 8 = $171. Times 2 for the pay period = $343, and $685 extra per month. Add another $685 per month per mandatory shift worked per week.
And then there's voluntary overtime which is time and a half for the first 4 and double time for the second 4 hours. You can figure your own formula for that ;)
There's plenty of earning potential on the ramp at Southwest even at step 1. And it only gets better as you move up the scale.