When should rent payments start?

[Kevin Noesner]

I have a retail building that needed some work and customization before the restaurant could open for business. We agreed that I would get it to a "vanilla box" state where it's up to code and then they would add the plumbing/electrical and other features needed for their business. Enter the muddy waters. Both our work has been happening simultaneously the last 6 months to avoid extra permits, drawings and inspections. I haven't received any rent yet and now we're deciding who should have paid for that time which went way over schedule. I have a lease that says they should pay for it but I also want to be fair with the delays that occurred. I verbally told them to hold the payments until July and I was ok with that as long as they made it back up after they open. What is typical for this type of retail shop that requires customization?