If your lease really ends the end of April, get pre-approved now. It takes time to find a place, get the mortgage processed and closed and for you to move. Usually with an FHA mortgage you are looking at 30 days for contract to closing but some lenders (and markets) take longer.
Pre-approvals usually last 90 days or so. It is nearly Feburary. Allow yourself some time to find the right place.
Yes, you may need your 2014 tax return filed first so file asap if you can.
Look for a lender the originates and funds their own loans - a correspondent lender or mortgage banker. Look for an experienced LO that can answer your questions and if s/he can't answer immediately, then they have access to the underwriter to get the answer.
A pre-approval can be issued quickly if you provide your paperwork quickly. If the lender won't give you a pre-approval in writing, that is a red flag. If the LO says "find the house first" that is a red flag. Any good, experiened LO can give you a pre-approval for what you qualify for with a max amount to spend on your taxes and insurance. When you do find a property you want to make an offer on, then the LO can redo the figures so you can see the actual costs for that property. You can then get a better estimate of closing costs.
Stay away from the big box banks (Wellls Fargo and BOA) - they will issue a pre-approval quickly but when it comes to actually closing they still have a large fall out rate. Not due to the buyer (usually) but due to their processing of the loan. I have seen many deals fall apart a day or two before closing when BOA or Wells is the lender. As a result, in my area most agents will be very wary of any offer made by a buyer using Wells or BOA to fund their loan...and you may actually lose the deal in a multi offer situation. No one wants to go under contract only to have the deal fall apart right before closing.
