Make sure your I-140 gets approved. If for some reason it gets rejected, all the underlying petition will be denied as well. If you are not in H1 to backup, then you will be considered out-of-status to bring more trouble. It is also advisable to file Premium Processing for I-140 in most of the cases. Or if you have already filed your I-140, you can upgrade to PP. About Immunization, if you have a Primary Care Physicial, you can make an appointment and have him/her to do the lab work. This will be covered by your insurance in most cases, (talk to your Insurance provider). PCP can order the tarter, which will get your immunization histroy. MMR, Chicken Pox, are needed for it. Also, STD and HIV are needed. If you can make an appointment to the county health clinic and request HIV and STD, it will be free. Once the blood tarter is done, it will show your past immunization if you have given Chicken Pox and MMR. Also, take tetanus shot. Once you have these all, make an appointment to USCIS surgon. It will save lot of money.