I've been doing a lot of thinking about you since last night, and I may have come up with an answer or two.
I've had the whole while to think since the first word I got about you.
He hadn't thought about them in a long time, since the day he'd left.
She had thought of this often since their first meeting.
"I have thought of you every day since last we met."
I've been doing nothing but thinking since the moment I realized.
I have thought about this matter a lot since that evening.
She had not thought about his surprise since that day.
I've been sitting here, thinking constantly since the moment you left.
I have never thought much of any females since that day.