The motion could either make the changes immediate or could apply only to positions elected in the next nomination/election cycle and later. Considering that your current slate of officers understood that they were agreeing to serve for only 1 year when elected, you may find resistance to a motion that doesn't grandfather their original term limit into this new motion.

Except for the term limit change, I would consider all other changes to be effective immediately.

The current officers ran and were elected for one-year terms. My question would be whether or not they could run again after this year. That would cause them to be in office for three years, which would be against the new bylaws.

Some bylaws may have a clause that says amendments take affect immediately while others may specify a time such as 30 days or at the start of the new school year. My last set of bylaws said nothing so we agreed that approved changes were immediate. I think it would be important to specify how it will be at your meeting so there are no assumptions or misunderstandings.

We will be voting on some changes to our bylaws tonight. One important change is the amount of time an officer serves. Currently an officer serves 1 year then we vote. The proposed change is that an elected officer will serve 2 years then vote and officer may serve no more than a 2 year term in same position. My question is, when do the changes take effect. Are they immediately in effect and if so does that mean that the current officers will now finish out this year plus one more year and then we vote again?
We are also looking at changing the amount of money that can be spent without prior approval from PTO member vote from 100 dollars to 200 dollars. Will this be in effect immediatley also.
Thanks for all of your help. I may be making this more confusing than it should be.