The IRS isn't known for being expeditious. However, if there are W-2s or 1099s and other reporting forms in your name, they are sure to get to it at some point.
Nevertheless, file the return as soon as possible and do your best to get every deduction and credit that you are entitled. If you do receive a notice in the interim, then call them and explain the situation to include that you are going to file the tax return as soon as possible.
Don't worry, you are not the first person to ever forget to file. In fact the taxing agencies are used to this situation.
If you owe money and you are not complete with the return, pay the balance as soon as possible since this stops penalties and interest on the amount due.
If you have any further questions, please do not hesitate to contact me.