Looking to read all your responses b/c we just set up our son for allergy shots as well. He, too, is 11. His worst titer was the C.herbarum (mold) and we have lots of deteriorating leaves on the ground around here year round (where that particular type of mold is mostly found-- in compost).
Our son has about 14 different allergens his bloodwork showed reactions on. So the serum they are making for him will be in 2 vials... one of the more severely reaction allergens, and one of the milder reaction ones. That way, we can up the dosage faster on the milder ones and he can get some relief sooner as regards those particular ones. The more reactive (higher titer?) ones we will have to "up the dose" at a little slower rate. We were told it will take between 1 and 2 years. Much faster (and higher success rate) than waiting until adulthood (3-4 years and lower success rate).
And yes, we were already told he will have to sit in the office and wait for a good 20 minutes after each treatment to watch for any adverse reactions, just in case. They have a video system and game chairs set up for their younger clients to use.
And nasal washes did nothing for my son. He actually likes doing them... but it doesn't help beyond the few minutes after he does it. And it won't stop a significant allergic reaction like he had last week. Exposure to something (probably the mold in some leaves he was bagging) followed by exercise brought on an asthma attack/event. Building immunity to the antigens will significantly reduce the potential threat from that happening again. A neti pot or other sinus rinse can't offer that peace of mind, as he won't be carrying one around on his person neti-potting/rinsing on hikes in the mountains during summer vacations, etc.