Dessert Nomad
Adventurer
Season 2 has one adventure with an optimal level of 1, five adventures with an optimal level of 2, four adventures with an optimal level of 3, three adventures with an optimal level of 6, and then three adventures with an optimal level of 8... Season 2's spread isn't too bad, and some of the adventures could be up- or downgraded to fill in the gaps. Season 3 seems a bit more sporadic, with nothing between 3rd level and 8th level and nothing between 8th and 12th.
How large is your home group, and how 'optimized' do they play? Most adventures have a section at the front to figure out how your group scales from 'very weak - weak - average - strong - very strong' based on the size or level of the group, and you use this to scale the adventure. In pickup play the DM is expected to adjust encounters (both using just the guidelines and their own judgement to add/remove enemies or obstacles). Also, my experience is that the majority of AL adventures are tuned for very softball combat encounters at the recommended level. This is going to be compounded in a home campaign, because your party will probably coordinate to have a mix of abilities (avoiding problems like 'no one is good in melee') and will know each other and be able to support each other better instead of sort of guessing on the fly. So even if the modules did line up with your party levels, you would still expect to do a lot of adjusting of encounters as you play.
(There really shouldn't be AL adventures with an optimal level at the edges of tiers (1, 4, 5, 9-10) because that takes away the room to adjust encounters; mathematically you'll never get a party with a higher average level than 4 in tier 1 or 10 in tier 2, and if you're doing pickup games getting a party at 4/10 requires you to have all players at that exact level, which is unusual. They make adventures like that sometimes for whatever reason, but you shouldn't expect the levels of modules to follow a progression.)
Are there any guidelines for using milestone advancement in AL adventures? I was going to use XP since it's nicely built-in, but I do actually prefer milestone leveling myself.
For people currently playing AL, they all effectively use milestones now. It takes 4 ACP to go up a level from 1 to 5, then 8 per level after that, you get 1 ACP for each hour the adventure is designed for or 1 ACP per hour advancing towards your goals when playing a hardcover. Some of the newer adventures have bonus objectives and other mods, but all of the older adventures run under what I said above now.