If you can get the H1 petition approved fully with the I-94 within U.S., your I-485 will not affected (till valid). The problem is that if your H1 petition is approved without I-94, you need to go outside US to get an H1 visa to activate it and this may affect your I-485 because your current status is not H1/H4. You can ask your employer to file the H1 petition for you now and if you do not get the I-94 with the H1 approval notice, you just use EAD to work and if your I-485 is denied, you can go outside US to get the H1 visa to activate it. If you are lucky to get the I-94 with the h1 approval notice, your status will h1 and your I-485 will be fine.