I wouldn't get a lawyer until/if they contact you, and if they do I wouldn't reply until you talk to the lawyer.
I trademarked a name about 7 years ago, it was a long process, and here's a few things that I learned (from a non-lawyer perspective):
1. Like you, I had a reasonably generic name (SaaS and Hub are two established English words, and they are both commonly used in software and IT services). That was the motivation for trademarking, as the chances are high that others will use similar names purely by chance as opposed to copying.
So I trademarked under a defensive strategy so others couldn't come for me, rather than an offensive strategy of going after others. The point is, come up with a reasonably original name (like Google) that isn't a an English word or a mash of English words, and you probably won't have to worry about trademarking.
2. To continue on from point 1, and let's say you create an original name, like Covfefe. You're doing business with it, then 2 years later you find out that someone else is trademarking it. The originality of the name should make it a lot easier to be notified when someone enters the process of trademarking. I think there's a 3-6 month process is which anyone else can object to it being trademarked, and if you've been using it and the company attempting to trademark it hasn't, then it will be thrown out.
In a challenge it comes down to who's been using it longer.
3. Given that somebody has already trademarked the name, and you missed the grace period to object, you could either wait for them to send a cease & decease (maybe that'll never happen if they're defensive like me), or you could change your name.