Hey brother. I feel your dilemma. I would say to get your climbing cert first. It will give you more opportunities and an advantage over people that don't have one. Most groundman jobs or at least edison,dwp, and local 47(at least to get a call) require it. What I have heard with the jatc as far as interviewing is to go in confident but not cocky. Use the 20 minutes to sell yourself. I too have an interview with them on the 16th. There is so much competition, it is gonna be tough. But its not impossible. I know a guy that got in last year without a cert. I've been unemployed for over a year now and I used that time to get my climbing cert, osha 10, cpr/first aid, and my class A. I think those are gonna be more important first. They do look for prior construction exp, not necessarily in the line field. I had 9 years in the plumbing trade. But I think I wouldn't have had the opportunities. I've had without the climbing cert and the class A. I coiuld be wrong but that's what I think. Hope it helps and good luck!