Hi Andrea,
This is my experience; I used to get lots of request to check-in early especially at my previous address. I've always had a check-in / out time which I include in my house rules even prior to Airbnb's new option. I rent a room in my home but I'm also self-employed as such I'm mostly busy out and about and have other commitments as well. Unlike hotels that have reception staff, I'm unable to wait at home all day or even throughout the entire check-in time frame for a guest to check in at a time of their choice; this is one of the many reasons that Airbnb is cheaper, there isn't a 24 hours check-in which means staff to pay and cost passed on to guest and my listing is priced at a quarter of a similar accommodation in a hotel so there is some give and take.
I used to have an additional house rule which stated that subject to availability and prior agreement between us, a guest might be able to check-in/ out outside of the specified time frame for a fee of £10, charged upfront via the extra charges - resolution centre. The guest would receive an e-mail with the additional charges which they accepted; alternatively, I also provided them with a list of temporary storage options. I have temporarily removed this option because I relied on my sister who is currently unavailable to offer this flexibility in exchange for the £10.
On receipt of a confirmed booking, I normally e-mail guest to say hello, thank you, confirm my contact numbers, offer travel directions from the airport or station and remind them of my check-in/ out times. In addition, I have a house rule requesting guest to confirm their ETA at least 12 hours in advance of arrival so I can plan around them and ensure there is someone at home to let them in. This indicates which guest might wish to check in earlier but have failed to inform me previously and we can discuss which option they prefer, my extra fee or the storage; most guests opt for my extra fee.
You still have to draw a line at an acceptable early or late check-in/ out time as I’ve had a couple of guest requesting to arrive as early as 15 hours in advance which I have outright declined as very unreasonable, in fact I would go as far as saying that is attempting to get a day more or less free.
I appreciate that sometimes there are travel delays which means the guest might arrive outside of my check-in time frame and I'm flexible to a degree give or take 60 - 90 minutes although I expect guest to communicate if the delays are particularly lengthy. I try to be flexible but I don’t promote it especially as I use Instant Booking, I like the guest to know where they stand upfront so they can make an informed decision as to if to book my listing or not.
This is an option I’ll offer again for an extra fee once my sister is in a position to stand in for me as I do receive such requests. I do this as standard for my other properties and it works well although those are not on Airbnb.
I hope this gives you some idea.
Ama