I have a job that doesn't require an LMO and I believe I am eligible to apply for a TWP at the port of entry and ahve all of the documentation that I need.

The job start date is August 1. I am planning a short trip to Canada in the first week of July (just 2 or 3 days) to do some reconnasance on housing, school etc.

Can I apply at the airport at that point (early July)? I am "entering" Canada in the day-to-day sense, but this will not be my "entry" in the sense of the moment relocation (which will be August).

It is generally possible to process a work permit request in advance of a stated start of work. The greater the duration between that start of work and the date of arrival at the port of entry, the more room for complication, however. Another option is to seek an advanced opinion on the viability for LMO exemption through a foreign worker unit within Canada and to seek visitor (temporary resident) admissibility for the purpose of reconnaissance.