Found an issue with the ISP and while I was fixing it I realized I could free up a pin to add an input. There is very little cost involved with adding the input which is a great thing. It significantly increases the things you can do with the timer by allowing it to react to an external input.
- added 2 pin terminal block for input via an Analog pin on TinyTimer.
- labeled load and input terminal blocks.
- connected input terminal block to VCC (5v) and a 100 ohm resistor -> ADC 3.
- Moved RED led off the serial clock line. It was causing the ISP to not work properly. Validated by cutting one lead on the prototype.
- Adjusted some component locations for easier assembly.
Here are some images related to the changes and improvments: