Hi there @Bippysan !
My first ping when reading your post is that you are incredibly apprehensive about having someone sit in your home and watch your pets - My 1st question would be, what is causing you the most concern?
-Is it their experience in pet sitting & whether or not they have the skills to care for your pets?
-Or is it having a stranger stay in your home?
Having been a sitter for many years (prior to being on this site) - I would say if you fall in the latter group and mainly the apprehension is having a complete stranger stay in your home - my 2 cents would be to try to find someone local who you can hire/book again and again, so that they are no longer a stranger. This is the pro of having local sitters (whether they be on TH or paid local sitters.) So you have someone you know and trust not only with your animals, but also tending to your beloved home. Entrusting your house with someone is no small handover IMO.
Having been a local sitter most of my time, an in person meet & greet is crucial for BOTH sides. You guys need to feel safe with this person and YES 1000% it is mostly an instinctual or gut feeling that this is a safe and trustworthy person. If you feel like anything is even slightly off or wonky, I would pass for your own peace of mind. This is your home and pets we’re talking about, so you want to feel absolutely at ease while you’re away, not always concerned about what’s happening at home. The sitter should be resonant to your energy (ie - not off putting to your baseline) be confident and at ease with your pets and home and have enough experience to ASK YOU certain pertinent questions also at the Meet.
Likewise, the sitter should be vetting you all. This is not a 1 way street IMO either. They should be making sure THEY feel safe and at ease in your home (lived in as it may be) to stay there for the duration, sleep there, eat there, etc. Feel confident and comfortable in the pet care required, etc.
I think it’s ok if your home is lived in - as long as the photos you post are accurate reflections of the state of your home. Most sitters just want something clean, that they don’t have to tidy and wipe down upon arrival. But this is also on them to discern & ask to see either in the meet or on video. I ask this in every video chat - a house tour - to make sure that what I’ve seen in the photos matches the actual state of the home.
Insofar as the sitter arriving prior to your departure, I believe that if you’ve already had a Meet and esp. if they live local, that is totally unnecessary. I find it actually less dramatic and hectic for me to arrive a few hours after the owners depart - giving them time to pack and depart with ease, allowing the home to settle, then arriving later. If the pets have already met me, it’s totally fine. However, when doing TH sits where I have not met them in person, I have found that arriving with enough time for an in person meet & orientation is more favorable to me personally, but I think that is a personal preference. I like to connect with the humans whose home I will be living in, get a IRL feel for them, and also I think it helps the pets to see us both together before I just arrive - a stranger - to their home and start taking care of them, you know? I think if the pets see me with their family and that all is peaceful, it will help them process me as the new person/sitter. But I don’t think that needs to be a nite before. I’ve arrived various times with only a few hours before the owners left. They just make it a priority to be packed & ready to go early, and carve out 1-2 hours for my orientation and it’s all gone very well! No need to host someone local for sure, esp if you’ve already met! Same goes with the end of the trip - I always leave a few hours before their arrival back home, so as to allow them to come home post-travel and not have to worry about tending to me.
Lastly, unless you feel super stellar about this 1 sitter after your meet and greet, like it was a very aligned match for sure - I wouldn’t hesitate to interview a few candidates! People do that all the time with sitters - on TH or paid local sitters - to find the right match for their pets and home. It’s worth the time and as long as you’re transparent with the sitters that it’s a process, I think that is fair.
Good luck out there!