I have to agree with Paul on everything he has said.
Some guys take wearing in their stride and others get quite anxious about it.
The important thing is that you get comfortable about it BEFORE testing it out on others.
If its a big step for you (& it sounds like it is) then you should consider taking some time out when you can be alone for say a long weekend.
You have to build your own confidence up. If you try it and you can see you look better, you will have a better grounding for facing others.
Start alone, then family, then with close friends and then work, strangers etc. and so forth.
The most likely give-a-way will be your attitude and not the replacement hair itself.
You won't get used to it over night, but you will be more comfortable about it every day that you carry on.
Knowing you look better is the biggest boost. You will be surprised when you get compliments and this will add to your confidence. Those compliments will be from people that notice you're looking good, but they won't know why. There are hundreds of posts from guys that have experienced EXACTLY that.
Getting a good fit & attachment can be a trial at the very start (for some) so you might want to consider getting it done professionally in the initial stages, with a good cut-in.
It can really help to talk to someone that knows their stuff and give you advice, rather than being alone and struggling and possibly getting worked up about it.
Best of luck and let us know how you get on.
PS. I just want to check that you do know that units come with surplus lace at the front which you cut back? Some cut it right up to the hairline and others leave a few millimetres in front of the hair.