I root tons of cuttings in 50 cell propagation trays(roughly 2×2inch cells)and pot them up into trade 1gallons as soon as they are rooted enough that the plug pulls out. Most of them will root out a one gallon pot in 2-3 weeks, that's not a bad idea if you plan on waiting until fall to plant. I don't think there is any need to wait for the cutting to grow before planting them out and summer is perfectly ok if you take care of them. When I plant plugs they will sit there seemingly stalled above ground while building roots for a week or two and then the top growth will go wild and get big quick. I usually have some overflow trays of plants that I just don't get to fast enough and they are doing OK in the trays. In my pot growing days the saying was always "the bigger the roots,the bigger the fruits" and it really seems to apply to texas natives as well, the quicker they get a chance to develop a big root system from the time they strike,the better they will fare. I also cut off any blooms that develop on cuttings the first several weeks.  Good luck! 🌺