请问to start with 与at first的用法是一样的吧

不一样!to start with(首先),相当于first或firstly,用于句首,表示事情发生的先后顺序.
而at first(起初,起先),用于表示“下一个动作与起初的完全不同,甚至相反”
试比较；
To start with,let's listen to some relaxing music.
At first,it's sunny.But now it's going to rain.