I started Aloe Polyphylla in December last year. I started them in a bagie in a well draining soil and fine grit mix, covered with only a fine layer - they need light to germinate.
I tried a few methods.
I put some in a heated propagator but none of those germinated.
The ones I put on the window ledge did eventually come but they took a long time, I'd basically given up on them but not gotten around to throwing them out before I noticed growth, so don't give up on them!
I also sprouted some in water. These ones germinated much faster and with over 80% success rate, BUT transferring them to soil is very tricky. The seeds themselves aren't small but the emerging root is very delicate, no matter how careful I was with them most of them didn't make it after transfer.
If I was starting them again I'd definitely do in on the windowsill, takes longer but the results are stronger healthier seedlings that have more chance of maturing into plants.
Mine have been very slow growing, I put them outside when the weather began to break in late spring, but we had an awful start to the summer, cool temps and even late hail storms. I also made the mistake of not giving them enough light at first, I was afraid of burning them but here in the UK they NEED full sun to grow. I now have one really good looking plant - if a bit small and several other mediocre looking ones that I'm hoping will pep up a bit next summer. I'm hoping to acquire a cold frame if we move house before the frost sets in, but if the move doesn't happen soon I'll over wintering them indoors and hope for the best.
I hope that helps a bit!
I'm waiting for the post man to drop a packet of Lithops seeds through my letterbox this morning, I love starting from seed, it's so exciting to see what emerges!