Karuri,
I'm a little confused.
Is the appraiser that you've spoken to expecting you to do three complete appraisals per day? If so, the answer is absolutely no, you cannot do it. In fact, I'll even go so far to say that if you have no background experience with the software programs you will be using, knowing how to choose and decide on comparable sales, measuring and knowing appropriate grid adjustments for your market area, you'll be stretched to the max just trying to get one appraisal finished in a weekend.
Correct me if I'm wrong here, but if this appraiser is someone who is considering you as a trainee, did you mention the kind of schedule that you spoke of in your original post (mostly weekends)? If so you'd better ask many more questions as to exactly what kind of supervision and basic training this person plans on giving you before they'll allow you to inspect and complete an appraisal. I also think you need to understand that as a trainee your supervisor should be present with you on your inspections, and not many would be willing to take a Saturday off to do that.
Something that most people don't realize about being an appraiser is that it's nearly impossible to get three homeowners to line up their appointments in a tidy order just to suit what works for your schedule, or to build a convincing case to your clients (the lenders) or supervisor that these are the only hours that you will be available. There are hundreds of other appraiser wannabes who would leap at the chance to work 24/7 if given the opportunity, and they'll set appointments at the homeowners convenience and complete the appraisal in the time frame dictated by the client.
It's no exaggeration when experienced appraisers tell newbies that they are going to be shocked at how much they DON'T know and can only learn if their mentor is continuously available to answer questions and provide guidance. It's a forumula for disaster, discouragement and failure if a newbie is thrown out into the field without proper one-on-one guidance for the sake of volume.
IMO, the idea of breaking into this profession on a part-time basis is nice but the reality is that most mentors will not be receptive to giving up their weekends to answer a million questions that most newbies will have. It's MUCH easier if the trainee is available at their supervisor's convenience during normal business hours.
I'm sorry if this post seems negative, but I believe it represents the reality of breaking into this business today. A few years ago I might have had a different opinion, but it's dog-eat-dog competition to get a foothold in the field right now unless you're fortunate enough to be training with an understanding family member or close friend.