In Indonesian the form of the verb does not change to indicate tense or aspect. Time can be indicated by a set of temporal markers within the predicate. These markers indicate that the action has occurred, is occurring, or is yet to occur in relation to moment of utterance or in relation to some other event referred to.

Adjuncts of Time

Time can be indicated by adjuncts of time such as:

setiap hari sebelum menjelang sekarang, kini akhir-akhir ini/baru-baru ini akhirnya tadi kelak tahun lalu, bulan lalu kemarin lusa tadi malam nanti sore malam-malam

everyday before approaching, towards now recently finally recently, a short while ago later last year, last month yesterday the day after tomorrow last night this evening late at night

tadi pagi sesudah sekitar dulu, dahulu mula-mula sebentar lagi nanti hari ini, bulan ini, tahun ini minggu depan/yang akan datang besok kemarin dulu tadi pagi pagi-pagi sore-sore

this morning after around, about earlier, previously at first in a moment soon, shortly today, this month, this year next week tomorrow the day before yesterday this morning early in the day late in the day

Examples:

Mereka berangkat tadi. Kita harus berangkat pagi-pagi. Pak Susanto pindah ke Surabaya tahun lalu. Dia pergi ke kantor setiap hari

They left a short time ago. We have to leave early in the morning. Mr. Susanto moved to Surabaya last year. He goes to the office everyday.

Sudah, Telah

Sudah and Telah have the same meaning. Those words usually indicate that an action has occured or that state has been achieved.
Examples:
Ali sudah bangun. – Ali has woken up.
Dia telah pergi. – He has gone.

Sedang, Lagi, Tengah

Sedang indicates that an action is in progress. Lagi and Tengah can replace sedang.
Examples:
Mereka sedang/lagi makan. – They are eating
Hotel itu tengah dibangun. – The hotel is in the process of being built.

Masih

Masih indictes that an action is still occurring. Like sudah, it can occur with other predicate types.
Examples:
Dia masih makan – She is still eating.
Dia masih muda – She is still young.

Akan, Bakal

These indicate a future event. If the point of reference is the past, akan indicates that something was going to happen(although sometimes it does not occur).
Examples:
Kami akan makan. – We will eat.
Dia bakal menjadi presiden. – He will become presidet.
Dia bakal presiden. - He is the future president.
Dia berjanji akan datang. – He promised he would come.

Baru

Baru indicates that an action or state has just occurred.
Examples:
Dia baru mandi. – He has just bathed.
Umurnya baru empat tahun. – She’s just four years old.

Pernah, Sudah, Telah

Pernah indicates that an action occurred in the far past. It can not be used of recent events. Sudah andTelah indicate that an action had occurred before another action.
Examples:
Dia pernah belajar di Paris. – She once studied in Paris.
Sebelum meninggal dia telah menceritakan riwayat hidupnya. – Before dying he had related his life story.
Ketika saya sampai di rumahnya Tomi sudah bangun. – When I arived at his house Tom had already got up.
Ketika saya sampai di rumahnya Tomi sedang makan. – When I arived at his house Tom was eating.

Reference:
Indonesian Reference Grammar by Dr. James Neil Sneddon