I'm probably the wrong person to ask. I work for myself and some of the work I do is connected to Scotland so I have met clients in a kilt. However in general I think a first interview in a kilt is a bad idea. I think a first interview should be memorable to the future employer for your qualifications and not for your outfit.

Also if the job would require a specific uniform or manner of dress that would prohibit a kilt then pass on it all together during the interview process. Only introduce the kilt if the employer is interested in you and a kilt would be a reasonable manner of dress for the job.