The best time to search for a space is when you don’t need it. This gives you a lot of leverage when you negotiate. It’s easy to walk away from negotiations if you’re not pressured to get into the space. This gives you a lot of leverage in the negotiations, if the landlord is anxious to lease it. Time is your friend.
If you’re under pressure, the next best thing is to fall in love with more than one space. Then you can walk away from negotiations if they aren’t going your way and revert to another option. The worst thing you can do is find one space, fall in love with it, and be under a time crunch. You won’t have much bargaining power under that scenario. You can still walk away, but then you’re back to square one.
Of course, the market will play a part in your negotiating strength. Your broker will help give you an idea of what the market is like.