this came up in a game, but we couldn't find a definite answer for this.

what's the exact timing for placing order tokens? are they issued one at a time or simultaneously? can i first issue one to leia and then use the move to get her into range of the second unit i want to issue an order to?

Oh dang that's a good question.

Sorry I don't have an answer...

There's nothing in the rules that implies it would be done simultaneously (even ignoring you being physically unable to do so!). The description of issuing orders on page 57 is procedural, describing the eligibility of each unit; none of the language indicates you must be checking all your units at the same time for these requirements. So yes, any game text that happens when a unit is issued an order will resolve before you issue your next order.

There's usually nothing to intervene, so I've always done them at the same time to save a minute, but that is a very perceptive question! How did it arise?

exactly as described. i wanted to order a commando strike team with a saboteur to get closer to the enemy for a great bomb spot, but leia was out of range for the order. the move1 was just enough to get her in range, so i just issued the order without much thought about the matter. my opponent asked if i'm sure that's how it's done and i was not. so we checked, but couldn't find anything conclusive on the subject in the rules reference.

i'm actually quite surprised this hasn't come up sooner.

Reading the RRG, page 21:

Issue Orders: Starting with the player who has priority, each player nominates a friendly eligible commander or operative and issues orders with that unit. The number of orders to be issued is indicated on the orders section of the chosen command card.
» If a commander-specific or operative-specific Command card is played, the player must nominate that commander or operative.
» If a non-operative-specific command card is played, the player cannot nominate an operative to issue orders.
» For a commander or operative to issue an order to a unit, that unit must be eligible to receive that order. To be eligible, a unit must meet all of the following requirements:
- The unit cannot have already received an order during the current Command Phase.
- The unit must be at range 1–3 of the nominated commander or operative.
- If a unit type (e.g., trooper) is specified on the chosen command card, the unit being issued an order must be of the specified type.

I understand that the orders are given one by one, so you could give and order to Leia, resolve the 1 move and then recheck range.