Will a TM30 be valid if filed 5 days before my arrival in Thailand?

You cannot file a legitimate tm30 until you are actually in the country.. it is the registration of your physical address in Thailand.. and the Thai property owner must file it within 24-hours of you checking in to your accommodation.. the online application doesn't necessitate uploading any of the foreigner's documents.. the account holder (your landlord) has to input your full name, date of birth, nationality, passport number, date of check-in.. this date being your first day as a resident in their accommodation.. there is an option to input length of stay (eg. x-nights) or to state the date you will leave the accommodation.. but this is optional rather than mandatory.. if a landlord files the tm30 before you are in the country it is technically invalid.. and when you go to request a certificate of residency from immigration they will almost certainly spot this.. and ultimately will reject your CoR application until your tm30 is regulatised.. and you could then find you are fined for filing the 'proper' tm30 late.. meaning if the re-filing date is later than 24-hrs after your passport stamp.. and if by chance they miss it (highly unlikely) when you go to extend your driving licence the disparity between your immigration stamp and the tm30 date could be picked up by an astute official there.. resulting in your DL application being rejected.. so you could be going round in circles.. there is absolutely no reason for a landlord to buck the system with an attempted early filing imo.. and even if they think they have 'beat the system' successfully it will likely come back to haunt you.. personally i'd tell them you'll be happy to provide a copy of your passport when you reach the property.. but there are so many possibilities that could unexpectedly delay your arrival.. cancelled or rescheduled flights, diverted flights, temporary airport closures, sudden ill-health etc.. that you really should wait and get your passport stamped on entry before engaging with online registrations.. with the exception of your TDAC of course 😉

When we use the TM30 portal, we can register someone up to 7 days before check in.... Not sure if it will be approved though considering you are out of country. I have registered friends staying with me early before but they have already arrived in Thailand. We don't actually upload any stamps when notifying persons of stay - that process is only used for the account holder during the registration process and when we need to register a new dwelling (sometimes). 🙏

In order for your landlord to submit your TM30 he needs foto copy for your passport data page and the entry stamp page he can't do it prior to your arrival

They will want both your entry stamp and your TM30 as part of the application to get a CoR, and they'll likely notice your TM30 is from before you entered Thailand and it will not be valid.